Which states are washed by the Indian Ocean? What continents is washed by the Indian Ocean? Which countries are washed by the Indian Ocean? Fisheries and marine industries

Geographical position

Indian Ocean ranks third in area and volume of water. It occupies 1/5 of the area of ​​the World Ocean and 1/7 of the surface of the planet (Fig. 1).

Rice. 1. Indian Ocean on the map.

Square Indian Ocean - 76.17 million km 2. Unlike the Pacific and Atlantic Oceans, it has a small number of seas, only 5. Temperature The surface layer of water is +17 °C, and the salinity is 36.5 ‰. The saltiest part of the Indian Ocean is the Red Sea, with a salinity of 41‰. Relief The Indian Ocean is unique: on the ocean floor there are 10 main basins, 11 underwater ridges and 1 trench more than 6 thousand meters deep.

Average depth The Indian Ocean is 3711 m, and the maximum is 7729 m. The coastline of the Indian Ocean is very slightly indented. Remember the location of the Indian Ocean objects: the Red Sea (Fig. 3), the Gulf of Aden, the Persian Gulf (Fig. 2), the Arabian Sea, the Bay of Bengal, the Greater Sunda Islands archipelago and the Mozambique Strait.

The most characteristic geographical feature The Indian Ocean is that 84% of its area is located in the Southern Hemisphere, and there is no direct connection with the Arctic Ocean.

Rice. 2. Persian Gulf

Rice. 3. Red Sea

According to modern data, the western border of the Indian Ocean is the meridian of 20° east. on the stretch between Antarctica and Cape Agulhas in southern Africa. In the northeast, its border runs along the shores of Asia to the Strait of Malacca along the islands of Sumatra, Java, Timor, New Guinea. Further east across the Torres Strait along west coast Australia and the islands of Tasmania. Further along 147° E. to Antarctica. The southern border of the ocean is the coast of Antarctica from 20° east. d. to 147° east. d. Northern border - the southern coast of Eurasia.

History of ocean exploration

The shores of the Indian Ocean are one of the areas of ancient civilizations. The exploration of the ocean began from the north by Indian, Egyptian and Phoenician sailors, who 3 thousand years BC. e. sailed in the Arabian and Red Seas and the Persian Gulf. The first descriptions of the routes of voyages in the Indian Ocean were made by the Arabs. For European geographical science, information about the ocean began to accumulate since the voyages Vasco da Gama(1497–1499) (Fig. 4), who, having rounded Africa, reached India.

In 1642–1643 Abel Tasman(Fig. 5) first passed from the Indian Ocean to the Pacific along southern shores Australia.

At the end of the 18th century, the first depth measurements were carried out here James Cook(Fig. 6).

A comprehensive and systematic study of the ocean began at the end of the 19th century with the circumnavigation of the English expedition on the Challenger ship (Fig. 7).

However, by the middle of the 20th century, the Indian Ocean was very poorly studied. In the 50s The Soviet expedition began work on the Ob ship (Fig. 8).

Today, the Indian Ocean is being studied by dozens of expeditions from different countries.

Lithospheric plates

At the bottom of the Indian Ocean there is a boundary of three lithospheric plates: African, Indo-Australian and Antarctic (Fig. 9). In the depression of the earth's crust, occupied by the waters of the Indian Ocean, all the large structural reliefs of the ocean floor are clearly expressed: shelf (accounting for more than 4% of the total ocean area), continental slope, ocean floor (ocean plains and basins, 56% of the total area ocean), mid-ocean ridges (17%), mountain ranges and underwater plateaus, deep-sea trench.

Rice. 9. Lithospheric plates on the map

Mid-ocean ridges divide the ocean floor into three large parts. The transition from the ocean floors to the continents is smooth, only in the northeastern part does the Sunda Islands arc form, under which the Indo-Australian lithospheric plate subducts. In this place, a deep-sea trench 4 thousand km long is formed. The deep Sunda Trench, like the underwater ridges, is a zone of active underwater volcanism and earthquakes.

Geological history of the ocean

Depression Indian Ocean is very young. It was formed about 150 million years ago as a result of the collapse of Gondwana and the moving apart of Africa, Australia, Antarctica and Hindustan. The Indian Ocean acquired its contours close to modern ones about 25 million years ago. Now the ocean is located within three lithospheric plates: African, Indo-Australian and Antarctic.

Climate

The Indian Ocean is located in the tropical and subequatorial zones of the Northern Hemisphere, as well as in all climatic zones of the Southern Hemisphere. Based on surface water temperatures, this is the warmest ocean. Temperature The Indian Ocean depends on latitude: the northern part of the ocean is warmer than the southern part. Monsoons also form in the northern Indian Ocean. The Indian Ocean washes the shores of big continent– Eurasia. Their interaction determines the features of surface currents and atmospheric circulation over northern part ocean and the southern coast of Asia. In winter, an area of ​​high atmospheric pressure forms over South Asia, and an area of ​​low pressure forms over the ocean. Thus, a wind is formed - the northeast monsoon. In summer, on the contrary, the southwest monsoon forms.

Sailors have long known the changing nature of the winds and currents of the northern part of the Indian Ocean and skillfully used it while sailing on sailing ships. In Arabic, “monsoon” means “season”, and “breeze” in French means “light wind”. Small sailing ships in the northern part of the Indian Ocean are still used.

Tsunami

Underwater earthquake in the Indian Ocean that occurred December 26, 2004, caused a tsunami that was considered the deadliest natural disaster in modern history. The magnitude of the earthquake, according to various sources, ranged from 9.1 to 9.3. This is the second or third strongest earthquake on record. The epicenter of the earthquake was in the Indian Ocean north of the island of Simeulue, located off the northwestern coast of the island of Sumatra (Indonesia). The tsunami reached the shores of Indonesia, Sri Lanka, southern India, Thailand and other countries. The height of the waves exceeded 15 meters. The tsunami caused enormous destruction and a huge number of dead people even in Port Elizabeth, South Africa, 6 thousand 900 km from the epicenter (Fig. 10).

Rice. 10. After the earthquake, December 2004

According to various estimates, from 225 to 300 thousand people died. The true death toll is unlikely to ever be known, as many people were swept out to sea.

Flora and fauna

Flora and fauna The Indian Ocean is quite rich. In the shallow waters of the tropical zone, corals grow, which create islands with red and green algae. Among the coral islands, the most famous are Maldives(Fig. 11). These robust coral structures are home to many species of invertebrates such as crabs, sea ​​urchins, sponges, coral fish. There are huge areas of dense thickets of brown algae here. IN open ocean Most of them are planktonic algae, and for Arabian Sea Characterized by blue-green algae, which constantly causes water blooms.

Rice. 11. Maldives

Also rich and animal world ocean. For example, among the animal waters of the Indian Ocean, the most common crustaceans are copepods, and siphonophores And jellyfish. The ocean is inhabited by squid, some species of flying fish, white shark, sailfish, poisonous sea snake, whales, turtles, and seals (Fig. 12). The most common birds are frigates and albatrosses.

Rice. 12. The underwater world of the Indian Ocean

The flora and fauna of the Indian Ocean is very diverse and interesting, as animals and plants live in a place favorable for development. This is a flower garden for nature lovers, environmentalists and tourists. Oil and natural gas are produced on the Indian Ocean shelf. The most famous place in the world for oil production is the Persian Gulf. The Indian Ocean is considered to be the most polluted by oil compared to other oceans. There are also many shipping routes in the Indian Ocean; there are large port cities and various places of recreation and tourism: Karachi, Dar es Salaam, Maputo, Mumbai, etc.

Bibliography

1. Geography. Land and people. 7th grade: Textbook for general education. uch. / A.P. Kuznetsov, L.E. Savelyeva, V.P. Dronov, series “Spheres”. – M.: Education, 2011.

2. Geography. Land and people. 7th grade: atlas, “Spheres” series.

1. Internet portal "Complete Encyclopedia" ()

2. Internet portal "Geography" ()

3. Internet portal "All about sharks" ()

All this is becoming a reality for tourists coming to Indian Ocean resorts.

The Indian Ocean Islands are an all-season luxury holiday destination. All you have to do is decide what you like best: relaxation and contemplation, active sports, the opportunity to touch antiquities or watch the most unusual creatures on Earth.

Mauritius

Tropical Mauritius was once a favorite haven of pirates, and now the island attracts thousands of tourists every year with its luxurious hotels and snow-white beaches, surrounded by mountains of volcanic origin. This place is suitable not only for heat-loving couch potatoes, but also for curious travelers who want to get acquainted with the amazing colonial architecture of the region, Indian temples and botanical gardens. Here you can also spot rare birds, walk through the park with lions or swim with dolphins, or you can even test your strength by doing extreme sports - wind and kite surfing are very popular on the island.

Mauritius is located just 20 degrees south of the equator, so the temperature here does not drop below +25° C. Most tourists go here on vacation when the cold weather sets in in the Northern Hemisphere, so peak tourist season on the island the period is considered to be from October to April. However, at this time of year it is quite hot and humid and sometimes rainy. The best time to holiday in Mauritius is the local winter, which begins in the Southern Hemisphere in May.

Mauritius is very small, only 45x65 square meters. km, however, due to the unique landscape, the weather here is very changeable. You are unlikely to be able to quickly get around this small island, and all because it is riddled with narrow and winding roads on which it is simply impossible to accelerate. In addition, when planning excursions, it is worth remembering that left-hand traffic has remained on the island since the British colonial era. Therefore, it is better for tourists to use taxi services or organized transfers.

The tourist center of Mauritius is the resort town of Grand Bay in the northeast of the island, where most hotels and entertainment venues are concentrated. The West Coast is the most expensive and prestigious: those who come here are accustomed to relaxing in the most luxurious hotels and want to sunbathe on the most beautiful white sand beaches. The south is considered the greenest, wildest and most interesting part of the island.

Where to stay

The pearl of Mauritius is Paradis & Golf Club on the Le Morne Peninsula. This hotel is considered one of the best on the southwest coast. It is especially memorable for guests due to the breathtaking views from the rooms of the picturesque beach and lagoon.

Paradis Resort is suitable for both those who want a relaxing holiday (there are several restaurants, a spa center of a famous cosmetic brand, the largest fitness center in Mauritius, its own international golf course and golf academy), and for those who prefer leisure and enjoys water sports. On the beach, hotel guests can use any equipment for free, including snorkel masks and windsurfing equipment. A separate fee will be asked only for the services of a personal instructor. By the way, this hotel hosts the Kite Jam Festival, which every year brings together professionals and amateurs of wind and kitesurfing from all over the world. The festival includes amateur competitions, master classes from world champions and the best athletes on the planet, as well as surfing and kiteboarding schools.

	Time zone: there is no time difference between Mauritius and Moscow. So it doesn’t matter how long your vacation is - you won’t remember what jet lag is after returning home.
	Visa: Visa for up to 60 days is issued upon arrival. To do this, at customs you must provide a passport valid for at least 6 months after the end of your stay in the country, a return ticket, a hotel reservation, a completed entry form and pay a fee of $17.
	How to get there: the best option is to fly with Air France to Paris with a connecting flight airlines Air Mauritius. Travel time including connections is about 16 hours. The price of a round-trip ticket is from 49 thousand rubles.

Madagascar

Madagascar is the largest island of the Indian Ocean, one of the poorest countries in the world, but at the same time it is among the most safe countries Africa. Such nature as in Madagascar cannot be found anywhere else. The flora and fauna of the island are rich in absolutely endemic plants and animals that cannot be found in other parts of the planet.

Baobab trees grow everywhere in Madagascar. In some areas, impressive rows of giant trees line up, in the crowns of which the African sun pancake beautifully “gets stuck” during sunset, giving tourists the opportunity to take photographs of amazing beauty.

Here you can see 70 species of lemurs and chameleons and even watch humpback whales. The best time to see whale migration is from June to September, but they appear in east coast waters year-round.

There is also a unique stone forest, covering an area of ​​more than 150 thousand hectares and representing sharp karst spiers, the approximate age of which is a million years. Stone Forest consists of intricate labyrinths through which excursions are organized for tourists.

As a rule, travelers go to Madagascar to see the jungle, wild animals, take part in safari or walk along adapted and safe tourist routes, which are complemented by several days of relaxation on the coast. The most popular recreation areas for foreign tourists are the resorts of the Anakao Peninsula and the beaches of the tiny island near Madagascar - Nosy Be.

The north of the country is very fond of divers all over the world, including those from Russia. The long coastline with unique underwater plants and animals gives them a completely new diving experience.

The climate of Madagascar is very diverse: on the coast it is tropical, in the interior it is closer to subtropical, and in the south it is dry (arid), with high air temperatures experiencing large daily fluctuations and with negligible amounts of precipitation. The island has two seasons. The hot and humid season - the Madagascar summer - lasts from November to April, the air temperature in these months is +25 + 27 ° C, the cooler dry season is established from May to October (+20 + 24 ° C).

Where to stay

One of the best hotels the popular resort island of Nosy Be - Ravintsara Wellness Hotel. “Fantastic vacation”, “royal vacation”, “heaven on earth” - these are the reviews from tourists that Ravintsara received for its beautiful and spacious bungalows on the beach, green gardens around, excellent service and exquisite cuisine. The hotel also offers entertainment for every taste: boat trips, ATV rides. The cost of accommodation is from 300 dollars per day.

	Time zone: Madagascar time is one hour behind Moscow.
	Visa: a tourist visa for up to 90 days can be issued upon arrival. To do this, you must provide a passport valid for at least 6 months and a return air ticket.
	How to get there: get to largest airport Madagascar Antananarivo from Moscow can be reached via Paris (Air France). Flight time is 14 hours excluding connections. Ticket price - from 50 thousand rubles.

Seychelles

The Seychelles is an archipelago of magical beauty, 115 islands, many of which are uninhabited, scattered in the waters of the Indian Ocean off the coast of East Africa. Breathtakingly secluded beaches, unique nature and climate make the islands perhaps the most idyllic tourist destination in the world.

Seychelles is one of the few resort areas, where you can simply pick up and fly away at any time of the year without worrying about seasonal weather changes. The climate here is quite stable throughout the year, the average air temperature on the islands is +26+30º C. During the peak season (December-January), precipitation on the islands becomes more frequent, which subsides only by mid-March, but it cannot be called abundant and essentially they do not interfere with tourists' recreation.

The warmest and calmest weather occurs in April-May and October-November. During this period on the islands ideal conditions for swimming, snorkeling and diving: water temperatures reach +29º C and visibility often exceeds 30 meters.

The period from October to April is the best time for fishing enthusiasts, and from April to October is the season for watching exotic birds. It is during these months that they reproduce, nurse their offspring and migrate to other regions. From May to September, fans of surfing and windsurfing flock to the Seychelles.

The main island of the archipelago, on which the international airport is located, is about. Mahe. Those who fly to the Seychelles in search of peace and secluded relaxation are unlikely to appreciate the bustle of Mahe, but it’s worth staying here if only to study the colonial architecture of the capital of the Seychelles - the city of Victoria, or to visit the botanical garden, which contains dozens of tropical species plants. The surrounding area of ​​Mahe Island has great opportunities for deep-sea diving: here you can not only swim with magnificent tropical fish, but also walk through the habitats of reef and big-nosed sharks, stingrays, sea urchins, and sea turtles.

Each island of the archipelago has its own atmosphere, and if you don’t want the noise of Mahe at all, then you can go to the small islands, where complete peace and quiet reigns.

Where to stay

One of best hotels Mahe - Banyan Tree Seychelles, located on the picturesque southwestern coast of the island. Banyan Tree has 60 villas, each with its own swimming pool.

This resort is located in quiet place, away from anything that might disturb you during your vacation. This sometimes makes guests think that they are on desert island, where someone invisible provides round-the-clock comfort. There are no entertainment venues or significant places nearby tourist places, so it is chosen by those who are going to enjoy a vacation away from civilization. The cost of renting a villa is from $1,200 per day.

	Time zone: on Seychelles The time coincides with Moscow.
	Visa: Russian citizens arriving in the Seychelles for a period not exceeding 30 days do not require a visa. It is placed at the border when entering the country.
	How to get there: you can fly from Moscow to the Seychelles by plane Emirates airlines with a transfer at your home airport (Dubai). Travel time including connections is 12.5 hours. Ticket price - from 30 thousand rubles.

Maldives

The Maldives is made up of about 20 groups of atolls, but only half of the islands that make up them are open to tourists. If you are planning to visit Republic of Maldives first time and are looking for some general recommendations on choosing a resort, then you need to remember the main thing: each of the Maldivian resorts is located on its own island, the sizes of the islands vary from 2.5 km to 150 m (from shore to shore). This means that all resort facilities (restaurants, bars, sports facilities, etc.) will be the only entertainment during your stay in the Maldives. Therefore, their infrastructure needs to be carefully studied in advance, so as not to fall into deep despondency on your long-awaited vacation. In general, there are offers for tourists for every taste: from affordable bungalows adjacent to diving equipment rental points, to secluded luxury villas on stilts in the sea, from the terrace of which you can hang your feet and admire the colorful fish swimming in the water.

The Maldives archipelago is located almost on the equator, the climate here is tropical, the temperature is stable all year round (about +28+30º C). The hottest season on the islands occurs in our winter: from December to April the islands are dry, and the air temperature reaches its highest levels.

Most of activities in the Maldives are centered around water activities. Snorkeling and diving are very popular - vacationers have the opportunity to see the most beautiful coral reefs and get acquainted with 700 species of exotic fish living in the Indian Ocean. Surfers (both advanced and beginners) also enjoy coming here to spend an invigorating holiday cutting through the waves on a board. Those who like a more relaxing holiday may be interested in fishing in open water.

Where to stay

One of the most famous Maldivian resorts, Shangri-La’s Villingili Resort & Spa, is located on the large and very picturesque Addu Atoll, on Villingili Island. Shangri-La offers accommodation in fully equipped traditional style villas. Guests can choose a house in the garden, on the shore or on stilts directly over the water. Vacationers have access to several restaurants, an outdoor swimming pool, a gym, kids club, a beauty salon and spa center that offers various facial and body care programs, scrubs, wraps, as well as massage and stone therapy. The territory has tennis and badminton courts, a small golf course, as well as everything you need for snorkeling, diving, windsurfing and fishing.

To the resort from international airport Tourists are transported to Male by plane or speedboat.

	Time zone: time on Maldives ahead of Moscow by an hour.
	Visa: Russian citizens do not need to apply for a visa in advance if the tourist flies into the country for a period of no more than 30 days. It is placed at the border upon entry into the country, for which you will need a valid passport and a dated return ticket.
	How to get there: international flights arrive at Hulule Airport, which is located next to the capital island of Male. Flights to the Maldives are regularly carried out by Emirates airlines (via Dubai), Singapore Airlines(via Singapore), Qatar (via Doha). Travel time depends on the length of the connection at the carrier's home airport. In the winter season, Aeroflot opens a direct flight to Male. Travel time is about 9 hours. The cost of the flight is from 49 thousand rubles.

O. Ceylon

The island of Ceylon (Sri Lanka) is a real corner of eternal celebration. The number of significant events celebrated here is more than 160 per year! Add to this colorful beaches, misty mountains, tea plantations and luxury hotels - and you get truly unforgettable vacation in the kingdom of nature on the shores of the Indian Ocean.

The developed tourism infrastructure in Sri Lanka provides vacationers with excellent opportunities for recreation for every taste: from “doing nothing” on the beaches and self-care in local spas to observing wildlife, practicing extreme sports and pilgrimages to ancient cities.

The climate in Sri Lanka is equatorial. It is warm and humid all year round, with the rainy season occurring in summer. The average annual air temperature on the island is +28º C, the water temperature in the Indian Ocean reaches +26º C.

The largest city island state- noisy, crazy Columbo. Tourists come here to get acquainted with the main attractions: admire the colonial buildings, mosques, churches, Buddhist and Hindu temples, see the presidential residence (or the Queen's House), visit National Museum and an art gallery. There is also a wonderful zoo in Colombo, where tourists try to go to the elephant show.

The beaches of the island are very popular among tourists. Moreover, Sri Lanka is gaining more and more popularity among those who love active sports. water sports. Surfers managed to fall in love with Arugam Bay, a place 314 km from Colombo, on southeast coast Ceylon, which was included in the honorary list of the ten best surf beaches in the world. Arugam Bay is popular among beginners, and for experienced athletes, the point of attraction has become the west coast, where you can catch impressive waves. The town of Negombo on the west coast of Sri Lanka has become a hangout for kitesurfers who come here for the winds from May to the end of September.

Thanks to the varied topography of the island, Ceylon has excellent conditions for rafting, the now fashionable hiking and mountain biking.

Wildlife lovers come to Sri Lanka to watch the whales and dolphins that appear in the waters near the town of Mirissa. At certain times of the year, sea turtles can also be seen coming ashore to lay eggs.

Where to stay

Most famous resort For beach holiday in Sri Lanka - the town of Bentota and its surroundings. This is where the largest number of hotels are located, offering accommodation for every taste. However, the hotels are located at a considerable distance from each other, so tourists can enjoy a relaxing holiday.

A beautiful secluded hotel in Benote - Saman Villas, which is located on a small rocky hill, right on the ocean. It is quiet and cozy here, the number of rooms (and especially the bathroom... open air) pleases travelers who do not skimp on positive reviews. Tourists also note the excellent cuisine in the hotel restaurant and praise the treatments at the local spa. The cost of living is about 300 dollars per day.

The small village of Hikkaduwa is popular among divers and surfers, who are known to be not too fussy, so there are mainly inexpensive hotels and apartments here.

You can snorkel and swim in the calm waters, which are protected from the waves by a coral ridge, at the Trincomalee resort, located on the east coast of the country.

	Time zone: time in Sri Lanka is 1.5 hours ahead of Moscow.
	Visa: Russian citizens do not need to apply for a visa in advance. It is placed at the airport upon arrival.
	How to get there: flights to Colombo are carried out Etihad Airlines(with a transfer in Abu Dhabi), Emirates (with a transfer in Dubai), as well as Aeroflot. Travel time is about 10 hours. The cost of a round-trip ticket is from 25 thousand rubles.

Irina Lavery

The maximum depth of the third largest Indian Ocean is 7209 m. This is the Sunda Trench, located in the eastern part of the oceanic space. The length of the bottom depression ranges from 4 to 6 km. On geographical maps this object is found under the second name - the Japanese arc.

The Indian Ocean simultaneously washes 4 continents of the globe. It is located south of the tropics called Cancer, covers the northern part of the Eurasian continent, touches the coast of Africa in the west, the border with Australia flows from the east, and the waters of the south wash the permafrost of Antarctica.

The dividing strip of the Indian Ocean with the neighboring Atlantic runs right through the area where Cape Agulhas is located. It is 20 degrees east longitude right up to the shores of Dronning Maud Land.

In the east, the extreme point of the Indian Ocean is located along the meridian of 146 degrees east longitude between Tasmania and Bass Strait. In the southern direction, the oceanic space stretches along the islands of Sumatra, Java, Bali, all the way to the Sunda Strait. Depending on water circulation and the time of year, the southern limit of the Indian Ocean can vary between 35 and 60 degrees latitude.

A few words about history

The maximum depth of the prehistoric Indian Ocean began to form in the Early Jurassic period, when a monolithic supercontinent called Gondwana began to break into separate parts. This is how Hindustan, the Arabian Peninsula, Australia, Africa and Antarctica were formed.

Geological process of formation of the present geographical relief ended only at the end of the Jurassic-beginning of the Cretaceous era. During the same period, about 140 million years ago, the floor of the Indian Ocean began to form.

During the Cretaceous era, there was an active movement of Hindustan, which increased the area of ​​​​ocean space. At the same time, there was a reduction in Pacific waters.

The Late Cretaceous era is characterized by the fact that at this time the Arabian Plate separated from the continent of Africa, the Red Sea appeared, as well as the Gulf of Aden. As a result of this process, the expansion of the Indian Ocean water area was completely completed.

The final stage in the formation of the boundaries of the water space, which have survived to this day, is the collision of Hindustan and the lithospheric plates of Asia. After this, tectonic processes remain relatively stable. The African plate continues to move, but not faster than 1-2 cm per year.

The most active is the Australian plate, which moves by 7 cm annually. This intensity of movement of tectonic plates is not capable of significantly changing the boundaries of the Indian Ocean and causing a new period of its historical development.

Square

In terms of water area, the Indian Ocean is in third place. Its total area is no less than 76 million square meters. km. The volume of the entire water mass is 283 million cubic meters. km. If we consider the Indian Ocean on a geographic scale, it occupies at least 20% of the entire area of ​​the globe.

Maximum width territorial waters– at least 10 thousand km. This is the length between the southernmost harbors of Australia and the African continent. Only the Pacific Ocean and the Atlantic are larger than the Indian Ocean.

Depth

Indian Ocean, whose maximum depth is 7209 m, also has shallow water areas. If we consider the average depth of ocean waters, they are 3711 m.

This is where the Sunda Trench is located. The most deep point Indian Ocean.

Maximum depths are located along the eastern coast of Japan. Much of the shallow water is found on the coral shelf of Australia's coastline.

Salinity

The degree of salt concentration in the waters of the Indian Ocean is heterogeneous. It depends on the speed of the current, as well as the area where the samples are taken. Average salinity levels are 34.8%. If we consider this aspect in territorial terms, then greatest number salt crystals are concentrated in the Persian Gulf and the waters of the Red Sea - this is 41%.

In tropical zones, the southern part of the Earth, as well as the Arabian Sea, salinity remains relatively high and reaches 36%. The lowest concentration of salt is only in the area of ​​the equatorial line and the waters washing the coast of Antarctica (no more than 34%).

Temperature

The Indian Ocean (the maximum depth of its waters keeps temperatures below 20 degrees Celsius) has a warm ocean surface. Maximum temperatures are observed near the equator. They reach 28 degrees and above when the sun is at its zenith.

Average temperatures are observed in the Arabian and Red Seas, as well as in the Persian Gulf (30-31 degrees). In winter, the coastal waters of the Australian mainland warm up to 29 degrees Celsius. On average, the water surface retains stable heat to a depth of 1-1.5 m.

Relief

The basis of the bottom relief of the Indian Ocean is the Indo-Australian segment. The bottom is divided into ridge mountains and depressions.

Oceanologists identify the following elevations that form the long ridge heights of the Indian Ocean:

The Indian Ocean (the maximum depth of water is concentrated in 5 places) has the following depressions:

• Sunda (trench);
• Arabian;
• Central;
• Coconut;
• Australian.

The bottom of the Indian Ocean is characterized by the formation of faults that appeared as a result of tectonic processes in the form of active movement of lithospheric plates and earthquakes. These are narrow and deep gorges called grabens. The most famous of them are the Ob and Diamatina.

The relief of the Australian coast of the Indian Ocean is represented by the Southern Basin, which is located along the entire continental part of the continent.

Climate

The Indian Ocean, whose maximum depth is more than 7000 m, is divided into 4 main climatic zones. They stretch along parallels and directly depend on underwater currents.

The northern part of the oceanic space is dominated by a monsoon climate, which is reflected in the weather conditions throughout Asia. The coast of this part of the continent is frequently affected by cyclones and heavy rains. These climatic conditions are typical for the winter season.

In summer, the climate of the Indian Ocean is influenced by the southwest direction of the monsoon, which causes strong wind 7 points, and the frequency of his gusts reaches 40%. The temperature of the water surface is between 28-32 degrees Celsius, and in winter it can drop to 22 degrees.

The southeastern climate zone produces the tropical trade wind, which blows throughout the year. Under its influence, most storms arise, waves more than 10 meters high are formed. average temperature this climate zone is not higher than 25 degrees.

The temperate continental and subtropical climate zone is characterized by warm summer(water temperature from 10 to 22 degrees) and not very cold winter (6-17 degrees Celsius). The lowest temperatures are observed only in the coastline of Antarctica - from +6 to -16 degrees.

Precipitation is heavy - up to 2.5 thousand mm throughout the calendar year. Zones of increased area (5 or more points) predominate. The only exception is the Arabian Sea region. The greatest cloudiness is observed in the waters surrounding Antarctica.

Currents

The northern waters of the Indian Ocean are characterized by seasonal changes in circulation directions, which depend on the movement of the monsoons.

The water cycle depends on the following currents:

Based on the above, we can conclude that the highest speed, deep water and high temperatures are characteristic of tropical and equatorial currents of the Indian Ocean. Closer to the Australian continent and Antarctica, water flows are not as fast and have low temperatures.

Which countries are washed by the Indian Ocean?

The following states on the list are located off the coast of the Indian Ocean and washed by its waters:

In addition, in the Indian Ocean there are island states, which do not have land borders with the continental part of the globe, namely:

• Madagascar (an island that for a long time was isolated from the continental part of the world, which served as the development of various species of animals represented exclusively in this corner of the globe);
• Sri Lanka;
• Reunion ( overseas territory France);
• Mauritius;
• Maldives;
• Antarctic territories;
• Comoros Islands.

The Indian Ocean has a direct impact on the formation of weather conditions in these regions, the development of the socio-economic sphere, as well as other vital processes.

Bays

The total area of ​​the bays and seas of the Indian Ocean is 11.6 million km. sq. This is at least 15% of the entire ocean surface. Most of the bays is located off the coast of states that are washed by the waters of the Indian Ocean, namely:

All of the above bays, with the exception of the Australian one, have a deep bottom and are part of basins. This bottom topography allows them to be used for shipping and port purposes.

Seas

All seas of the Indian Ocean have coastlines, they are used for fishing, and in some there is mining.

Most of the reservoirs have a name consonant with the territory they wash, namely:

• Arabian Sea;
• Krasnoe (bottom areas are rich coral reefs appropriate color);
• Davis Sea;
• Adamanskoe;
• Sea of ​​Cosmonauts;
• Timorese;
• Arafura;
• Mawson Sea.

The latter body of water is mistakenly included in the Southern Ocean, which is incorrect. Depth, temperature and climate inland seas oceanic space - are heterogeneous, depending on their location, fullness and currents that pass through them.

Islands

Every second island in the Indian Ocean is considered a fragment of ancient continents, which were broken into fragments during the active movement of lithospheric plates. As a result of these geological transformations that took place in Early Jurassic, Jurassic and Cretaceous periods, on today's world map there are the following island territories:

Most of the above islands are inhabited by people, are part of continental states, or form independent republics with developed infrastructure, economy, and tourism industry. The only exceptions are archipelagos and territories located on the shelf of Antarctica.

Inhabitants

The flora and underwater world of the Indian Ocean is rich and diverse. In the tropical zone there is an accumulation of plankton. The most common is the algal organism Trichodesmium, which has a unicellular structure. It develops quickly and acts as a nutritional basis for a large number of fish and crustaceans.

Plankton is represented by the following types of organisms that have a glow effect at night:

In the cold waters washing the coast of Antarctica, the fauna is also represented by some species of plankton, which are capable of developing in temperatures close to 0 degrees Celsius, namely:

• diatoms;
• copepods;
• Euphausids.

Fish remain numerous representatives of the underwater world of the Indian Ocean.

The following species can be found in these waters:

• nototheniaceae family;
• Coryphenes;
• tuna;
• mackerel;
• almost all types of sharks.

Reptiles are represented by giant turtles and snakes, whose bodies are adapted to living in salt water. Mammal inhabitants of the Indian Ocean are humpback, toothless and blue whales, seal species, and a large number of dolphins.

Their habitat is located in the circumpolar and temperate continental latitudes of the oceanic space, where mixing of warm and cold water flows occurs, creating comfortable environment for the growth of the plankton population, which is a nutritional base. Bird species such as frigate birds, penguins and albatrosses live here.

Underwater plants of the Indian Ocean are brown algae (turbinaria, sargassum), as well as blue-green algae in the form of caulerpa. The Australian coastline is represented by halimeda, lithothamnia, calcareous polyps, which live in a single symbiosis with corals.

In the south and closer to the eastern part of Asia, a large number of mangrove forests are concentrated in Madagascar. Kelp, gelidium, fucus, and gelidium grow in the waters of Antarctica. The flora of the polar coasts is represented by giant macrocystis algae.

Fisheries and marine activities

Despite the fact that a large number of fish species are concentrated in ocean waters, their global catch is considered small, accounting for only 5% of the fishery.

The main commercial fish species of the Indian Ocean are:

Tiger shrimp, lobsters and squid are subject to commercial catch. Until the end of the 20th century, whale hunting was developed in the South Indian Ocean. Today, their production has practically ceased due to the massive destruction of large blue whales, which are on the verge of extinction.

In Sri Lanka, the western and northern coasts of Australia, as well as in Bahrain, pearls are mined, which are of natural origin, and a small part is grown artificially in the harbors of the Indian Ocean.

Minerals

The most valuable natural resources of the Indian Ocean remain gas and oil deposits.

Large sources of fossils are found in the depths of the seabed Persian Gulf. Hydrocarbon exploration and production is also underway in the Bassi Strait near the territory of Hindustan.

Deposits of monazite, zirconium, ilmenite and titanite are being developed on the coastlines of countries such as Mozambique, Sri Lanka, Tanzania, Madagascar, and the South African Republic. Cassiterite is mined in the waters of the Australian continent, India and Thailand.

Interesting facts about the Indian Ocean

The Indian Ocean, as part of one of the 4 elements of the globe, has its own characteristics, specific differences, as well as episodes of its own history that are interesting for any person who wants to know more information about the planet. Here are a few amazing facts about the Indian Ocean.

Cradle of Civilizations

The Indian Ocean coast is where the Earth was first mass populated with dense settlements.

Residents of various tribes living in South-East Asia, used homemade boats reminiscent of modern catamarans and junks, set sail and, during the period when the Western monsoon blew, migrated to the Eastern part of Africa. There the settlement of this continent began with representatives of another continent and civilizations.

Trade routes

It is known that even 3500 BC. The Arabian Sea, which is part of the Indian Ocean, was actively used by the Ancient Egyptians for trade with Persia and the then states of the Arabian Peninsula. The inhabitants of Mesopotamia made trade expeditions to India and Arabia.

At the same time, the waters of the Indian Ocean were used not only for the movement of trade goods, but also interstate relations were established.

Hostilities

After Alexander the Great completed his land campaign against India, which from a military point of view did not end very successfully, in 325 BC. The Greeks used a huge flotilla of up to 100 ships, made a long voyage and landed on the banks of the Indus River.

This was the first sea voyage of an army of five thousand, which was able to overcome the severe storm conditions of the Indian Ocean and reach its destination.

First discoveries

In the 12th century, the famous Italian navigator Marco Polo, returning from China, passed through the entire length of the Indian Ocean, starting from the Strait of Malacca to the waters of Hormuz, explored the island of Sumatra, the shores of Ceylon, and also India. All information about the trip and data on the research carried out were presented in the famous book, which was called “On the Diversity of the World.”

Today its contents will not surprise anyone, but at that time it contained valuable knowledge for sailors, writers and cartographers around the world.

Australia Exploration

In 1642, a maritime company from the Netherlands, consisting of 2 ships, conducted a research expedition to study the central and eastern latitudes of the Indian Ocean. The expedition was led by Captain Tasman.

In the course of the research, it was established and scientifically proven that Australia is an independent continent that has no contact with other continents and other land segments. During the same period, an island was discovered and named after the leader of the scientific expedition - Tasmania.

Plane crash

In 2014 maximum depths The Indian Ocean was explored using the latest equipment, careful mapping of the bottom topography was carried out, as a result of which the world learned about new ocean ridges, depressions, faults, mountain heights and areas of volcanic activity.

The reason for such extensive research work was associated with an extensive search for a Malaysian Airlines Boeing 777, which disappeared from radar in the south-eastern part of the ocean.

Article format: Mila Friedan

Video about the Indian Ocean tsunami

Nat Geographic. About the tsunami in the Indian Ocean:

One of most popular resorts The destination that many tourists from all over the world flock to is Goa. But some vacationers have a question: what kind of sea or ocean is in Goa?

This is a very important question, because sometimes this geographical conditions depends on the ability to swim to your heart's content in a body of water, since, for example, the ocean coast can be dangerous (a large number of sharks, poisonous jellyfish), while the sea coast is created for active water recreation.

Indian pools

If you are wondering what awaits you on the coast (sea or ocean), get ready to receive several answers, contradictory to each other.

Read how to get to Goa by plane, and how long the flight lasts.

Is there an ocean or a sea in India?

From the west, India is washed by the waters of the Arabian Sea, from the east by the Bay of Bengal, a small southern part by the Laccadive Sea, and the union territory of the Andaman and Nicobar Islands is washed by the waters. All these bodies of water, in turn, are part of the Indian Ocean.

Which body of water surrounds North and South Goa?

For many inexperienced tourists who decide to go on their vacation to Goa, the question always remains open: what waters wash the resort: marine or oceanic.

The answer here lies on the surface: Goa is located in the west of India, and accordingly, is washed by the Arabian Sea.

Considering that the Arabian Sea is an open part of the Indian Ocean, it can be said that there is both sea and ocean. In the oceanic part of the waters of Goa, sharks are rarely found; large concentrations of them are found off the coast of Oceania.

Sharks also love reef areas, so divers need to be careful when diving. Found in the Indian Ocean tiger, gray and great white shark, and the most dangerous resorts in these waters are Kosi Bay in South Africa, Seychelles, and resorts in Australia.

Holidays in Goa

It should be noted that a beach holiday is not the strongest point state of Goa.

Coast

sea ​​coast North Goa and Yuzhny is not much different. Perhaps the only visible difference is sand. In the southern part of the resort the sand is whiter. Due to this, it visually seems that the beaches here are cleaner and the sea is more transparent. In the northern half of the resort from Sinquerim-Candolim to Anjuna, the sand is more yellow with a grayish tint, and is coarse.

In general, we can say that lovers of clean “paradise” beaches will have a hard time here, since the Indian mentality is rather indifferent to garbage, so you can talk about cleanliness and order here forget.

The sea waters here seem cloudy, because it is constantly agitated and mixed with sand and clay from the coast, so those who like to dive off the coast with a mask will have to abandon the idea. Many tourists speak unfavorably about the coast of the northern part of the resort, since the bottom of the coastal waters here is strewn with sharp stones, which can easily injure you.

Find out what time of year it is the best way Suitable for a holiday in Goa.

In addition to the uneven bottom, dirty sea and unattractive beaches, here you may encounter, for example, cows freely moving along the coast. So for those who love an unusual holiday, there will be something to remember after the trip.

Beaches

For those who cannot decide on a beach, here are some of the most popular beaches in both North and South Goa:

Agonda. Agonda can be called a “wild” beach, since here you will not find any restaurants, hotels, or spas. This is just a strip of sand stretching for three kilometers along the sea. This place is suitable for those who do not like noise and bustle, and prefer solitude and contemplation of the roaring waves to active recreation.

Here you can rent a tent, sun lounger, umbrella and give yourself relaxing holiday. A cafe or restaurant can be found further from the beach, in the palm thickets, but even there it is rare.

The current here is quite strong, so for those who are not very good swimmers, it is better to choose another beach for relaxation.

Anjuna. This beach is created for those who love active holidays with loud music, entertainment and big amount alcohol of your choice. In the 70s of the last century, this beach was swarming with hippies, so parties here have a special atmosphere.

Besides entertainment program, next to this beach there is a flea market on Wednesdays where it seems you can buy the whole world. Due to constant “parties”, this beach accumulates a lot of trash, which no one is in a hurry to clean up, so it can harm a normal beach holiday.

Arambol. One of the longest beaches in North Goa. It stretches for as much as 17 kilometers along the sea and is considered quite comfortable place for swimming. There are not very many people here, the coast is mixed: there is sand and pebbles, in some lagoons there is both salt water and fresh water, so there are suitable conditions for everyone.

Also close to the beach there is lake, where many tourists seek health (supposedly the mud of this lake is medicinal). There are also parties here, but they are less grandiose than on Anjuna, because different people with different needs relax on Arambol.

• Calangute. This beach is considered the most popular in Goa. A huge number of tourists flock here every year. It is especially crowded here from December to February, there is practically no crowd. Due to such an influx of vacationers, the infrastructure here is maximally developed. There are a huge number of restaurants, cafes, bars, and clubs, so you definitely won’t get bored.



• Benaulim. Another option for those who prefer peace and quiet. Most often, tourists from Europe come here and organize their own vacation. The infrastructure here is quite developed, so you will definitely be guaranteed a comfortable and relaxing holiday.
• Colva. One of the representatives of South Goa, popular among Indians. You rarely see foreign tourists here, which is quite strange, because Colva is a beautiful wide beach that is literally created for a quiet, comfortable holiday. Here you can get a good tan, swim to your heart's content, and then relax in one of the hotels (there are more than enough of them here).

Palolem. Another representative of the southern part of the resort. This is a very quiet resort in terms of sea conditions - there are practically no waves here. This resort is suitable for those who prefer exotic holiday traditional.

The infrastructure here is poorly developed, hotels are rare, cafes and bars are practically impossible to find.

Vacationers live in huts. On the plus side: this type of vacation is very romantic. The downside: these huts don’t have the usual amenities we are used to. Frequent departures from here excursion groups, fishing lovers will also find something to do here.



Cooking. This beach is very popular among hardcore tourists. There are enough vacationers here (not too many and not too few), the beach itself is quite clean, calm, with white sand.

There is plenty of space for relaxing sunbathing and swimming, and for those who want to grab a bite to eat or drink, there are plenty of restaurants and bars, as well as hotels to suit all tastes. This place is ideal for tourists with average incomes who prefer a relaxed holiday.

Entertainment

In addition to a beach holiday, Goa has a number of entertainment options, among which you can find something that suits you to make your vacation memorable for a long time.

Read in what natural and man-made attractions are worth visiting in North and South Goa.

From water activities, which can be combined with a passive beach holiday, are presented:




In addition to water activities, there are land excursions. For example, a popular excursion remains elephant riding. There are not many elephants here, but it is not difficult to find those who provide the opportunity to ride this animal. Sometimes they even offer swimming with elephants, if excursion route passes next to a waterfall or spice plantations.

For those who like to experience another culture, there are Indian dance courses, cooking courses, and yoga.

Extreme lovers can purchase tickets for bullfights- spectacles that are held spontaneously, without special arenas or preparation.

A little about seasonality

In addition to the place of rest, you need to choose the time of rest. High or low season, large or small number of tourists, high or low prices- all this is very important when organizing a vacation.

High season begins in Goa around December and ends in February. It is in December that the most diverse public strives to get a unique golden tan, as well as to swim in the sea to its heart's content.

Water temperature in high season it is not much different from other times in Goa, it ranges from +26 to +29 degrees. You can swim in Goa all year round, so you don’t have to choose a tourist peak for this. The air temperature ranges from 29°C to 31°C all year round.

Silence covers Goa in May, this month the parties die down, hotels empty, restaurants and cafes close. May days bring in Indian state stifling heat, stuffiness and rainy season.

Water the sea warms up to +30 degrees, with constant waves and such temperatures it is impossible to swim. The only advantage of a holiday in the low season, perhaps, will be the prices.

The Arabian Sea coast in Goa is next video:

INDIAN OCEAN, the third largest ocean on Earth (after the Pacific and Atlantic), part of the World Ocean. Located between Africa in the northwest, Asia in the north, Australia in the east and Antarctica in the south.

Physiographical sketch

General information

Border of I. o. in the west (with the Atlantic Ocean south of Africa) along the meridian of Cape Agulhas (20° E) to the coast of Antarctica (Donning Maud Land), in the east (with the Pacific Ocean south of Australia) - along the eastern border of the Bass Strait to the island of Tasmania, and then along the meridian 146°55"" E. to Antarctica, in the northeast (with a swimming pool Pacific Ocean) – between the Andaman Sea and the Strait of Malacca, then along the southwestern coast of the island of Sumatra, the Sunda Strait, the southern coast of the island of Java, southern borders the seas of Bali and Savu, the northern border of the Arafura Sea, the southwestern shores of New Guinea and the western border of the Torres Strait. The southern high-latitude part of the I. region. sometimes referred to as the Southern Ocean, which combines the Antarctic sectors of the Atlantic, Indian and Pacific oceans. However, such geographical nomenclature is not generally accepted, and, as a rule, I. o. considered within its usual boundaries. And about. - the only one of the oceans that is located b. hours in the Southern Hemisphere and is limited in the north by a powerful land mass. Unlike other oceans, its mid-ocean ridges form three branches radiating in different directions from the central part of the ocean.

Area I. o. with seas, bays and straits 76.17 million km 2, water volume 282.65 million km 3, average depth 3711 m (2nd place after the Pacific Ocean); without them - 64.49 million km 2, 255.81 million km 3, 3967 m. The greatest depth in the deep sea Sunda Trench– 7729 m at point 11°10"" S. w. and 114°57"" E. e. The shelf zone of the ocean (conditionally depths up to 200 m) occupies 6.1% of its area, the continental slope (from 200 to 3000 m) 17.1%, the bed (over 3000 m) 76.8%. See map.

Seas

Seas, bays and straits in the waters of the island. almost three times less than in the Atlantic or Pacific Oceans, they are mainly concentrated in its northern part. Seas of the tropical zone: Mediterranean - Red; marginal - Arabian, Laccadive, Andaman, Timor, Arafura; Antarctic zone: marginal - Davis, D'Urville (D'Urville), Cosmonauts, Mawson, Riiser-Larsen, Commonwealth (see separate articles on the seas). Largest bays: Bengal, Persian, Aden, Oman, Great Australian, Carpentaria, Prydz. Straits: Mozambique, Bab el-Mandeb, Bass, Hormuz, Malacca, Polk, Tenth Degree, Great Channel.

Islands

Unlike other oceans, the islands are few in number. The total area is about 2 million km 2. Most large islands mainland origin - Socotra, Sri Lanka, Madagascar, Tasmania, Sumatra, Java, Timor. Volcanic islands: Reunion, Mauritius, Prince Edward, Crozet, Kerguelen, etc.; coral - Laccadive, Maldives, Amirante, Chagos, Nicobar, b. including Andaman, Seychelles; The coral Comoros, Cocos and other islands rise on volcanic cones.

Shores

And about. It is distinguished by a relatively small indentation of the coastline, with the exception of the northern and northeastern parts, where the bays are located. including seas and major large bays; There are few convenient bays. The coasts of Africa in the western part of the ocean are alluvial, weakly dissected, and often surrounded by coral reefs; in the northwestern part - indigenous. In the north, low, weakly dissected shores with lagoons and sand bars, in places with mangroves, bordered on the landward side by coastal lowlands (Malabar Coast, Coromandel Coast) predominate; abrasion-accumulative (Konkan coast) and deltaic shores are also common. In the east, the shores are indigenous; in Antarctica, they are covered with glaciers descending to the sea, ending in ice cliffs several tens of meters high.

Bottom relief

In the bottom relief of the I. o. Four main elements of geotexture are distinguished: the underwater continental margins (including the shelf and continental slope), transition zones, or island arc zones, the ocean floor and mid-ocean ridges. The area of ​​the underwater continental margins in the I. region. is 17,660 thousand km 2. The underwater margin of Africa is distinguished by a narrow shelf (from 2 to 40 km), its edge is located at a depth of 200–300 m. Only near the southern tip of the continent does the shelf expand significantly and in the area of ​​the Agulhas Plateau extends up to 250 km from the coast. Significant areas of the shelf are occupied by coral structures. The transition from the shelf to the continental slope is expressed by a clear bend in the bottom surface and a rapid increase in its slope to 10–15°. The underwater margin of Asia off the coast of the Arabian Peninsula also has a narrow shelf, gradually expanding on the Malabar coast of Hindustan and off the coast of the Bay of Bengal, while the depth on its outer border increases from 100 to 500 m. The continental slope is clearly visible everywhere along the characteristic slopes of the bottom (height up to 4200 m, Sri Lanka island). The shelf and continental slope in some areas are cut through by several narrow and deep canyons, the most pronounced canyons being underwater continuations of the channels of the Ganges rivers (together with the Brahmaputra River, it annually carries about 1,200 million tons of suspended and traction sediments into the ocean, forming a layer of sediment over 3,500 m thickness). The Indian Ocean margin of Australia is characterized by an extensive shelf, especially in the northern and northwestern parts; in the Gulf of Carpentaria and the Arafura Sea up to 900 km wide; the greatest depth is 500 m. The continental slope to the west of Australia is complicated by underwater ledges and individual underwater plateaus. On the underwater outskirts of Antarctica, there are everywhere traces of the influence of the ice load of the huge glacier covering the continent. The shelf here belongs to a special glacial type. Its outer boundary almost coincides with the 500 m isobath. The shelf width is from 35 to 250 km. The continental slope is complicated by longitudinal and transverse ridges, individual ridges, valleys and deep trenches. At the foot of the continental slope, an accumulative plume composed of terrigenous material brought by glaciers is almost everywhere observed. The largest bottom slopes are observed in the upper part; with increasing depth, the slope gradually flattens out.

Transition zone at the bottom of the I. o. stands out only in the area adjacent to the arc of the Sunda Islands, and represents the south- eastern part Indonesian transition region. It includes: the Andaman Sea basin, the Sunda Islands island arc and deep-sea trenches. The most morphologically pronounced in this zone is the deep-sea Sunda Trench with a slope steepness of 30° or more. Relatively small deep-sea trenches are identified to the southeast of the island of Timor and east of the Kai Islands, but due to the thick sedimentary layer, their maximum depths are relatively small - 3310 m (Timor Trench) and 3680 m (Kai Trench). The transition zone is extremely seismically active.

Mid-ocean ridges I. o. form three underwater mountain ranges radiating from the area at coordinates 22° S. w. and 68° E. to the northwest, southwest and southeast. Each of the three branches is divided according to morphological characteristics into two independent ridges: the northwestern - into the Middle Aden ridge and Arabian-Indian Ridge, southwestern – on West Indian Ridge and the African-Antarctic Ridge, southeastern - on Central Indian Range And Australasian-Antarctic Rise. That. median ridges separate the bed of the I. o. into three large sectors. The median ridges are vast uplifts, fragmented by transform faults into separate blocks, with a total length of over 16 thousand km, the foothills of which are located at depths of the order of 5000–3500 m. The relative height of the ridges is 4700–2000 m, width 500–800 km, depth of rift valleys up to 2300 m.

In each of the three sectors of the ocean floor, the I.O. characteristic forms of relief are distinguished: basins, individual ridges, plateaus, mountains, troughs, canyons, etc. In the western sector there are the largest basins: Somali (with depths of 3000–5800 m), Mascarene (4500–5300 m), Mozambique (4000–5800 m), 6000 m), Madagascar Basin(4500–6400 m), Agulhas(4000–5000 m); underwater ridges: Mascarene ridge, Madagascar; plateau: Agulhas, Mozambique; individual mountains: Equator, Africana, Vernadsky, Hall, Bardin, Kurchatov; Amirantsky Trench, Mauritius trench; Canyons: Zambezi, Tanganyika and Tagela. In the northeastern sector there are basins: Arabian (4000–5000 m), Central (5000–6000 m), Coconut (5000–6000 m), North Australian (Argo Plain; 5000–5500 m), Western Australian Basin(5000–6500 m), Naturalista (5000–6000 m) and South Australian Basin(5000–5500 m); underwater ridges: Maldives Ridge, East Indian Ridge, Western Australian (Brocken Plateau); mountain range Cuvier; Exmouth plateau; Mill Hill; individual mountains: Moscow State University, Shcherbakova and Afanasy Nikitin; East Indian Trench; Canyons: Indus, Ganges, Seatown and Murray rivers. In the Antarctic sector there are basins: Crozet (4500–5000 m), African-Antarctic Basin (4000–5000 m) and Australian-Antarctic Basin(4000–5000 m, maximum – 6089 m); plateau: Kerguelen, Crozetand Amsterdam; separate mountains: Lena and Ob. The shapes and sizes of the basins are different: from round with a diameter of about 400 km (Comoros) to oblong giants with a length of 5500 km (Central), the degree of their isolation and the bottom topography are different: from flat or gently undulating to hilly and even mountainous.

Geological structure

Feature of I. o. is that its formation occurred both as a result of the split and subsidence of continental massifs, and as a result of the spreading of the bottom and the new formation of oceanic crust within the mid-ocean (spreading) ridges, the system of which was repeatedly rebuilt. The modern mid-ocean ridge system consists of three branches that converge at the Rodriguez Triple Junction. In the northern branch, the Arabian-Indian Ridge continues northwest of the Owen transform fault zone with the Gulf of Aden and Red Sea rift systems and connects with the intracontinental rift systems of East Africa. In the southeastern branch, the Central Indian Ridge and the Australasian-Antarctic Rise are separated by the Amsterdam fault zone, which is connected to the plateau of the same name with the volcanic islands of Amsterdam and Saint-Paul. The Arabian-Indian and Central Indian ridges are slow-spreading (spreading speed is 2–2.5 cm/year), have a well-defined rift valley, and are crossed by numerous transform faults. The wide Australasian-Antarctic Rise does not have a pronounced rift valley; speed spreading it is higher than in other ridges (3.7–7.6 cm/year). To the south of Australia, the uplift is broken up by the Australian-Antarctic fault zone, where the number of transform faults increases and the spreading axis shifts along the faults in a southerly direction. The ridges of the southwestern branch are narrow, with a deep rift valley, densely crossed by transform faults oriented at an angle to the strike of the ridge. They are characterized by a very low spreading rate (about 1.5 cm/year). The West Indian Ridge is separated from the African-Antarctic Ridge by the Prince Edward, Du Toit, Andrew-Bain and Marion fault systems, which shift the ridge axis almost 1000 km to the south. The age of the oceanic crust within the spreading ridges is predominantly Oligocene-Quaternary. The West Indian Ridge, which penetrates like a narrow wedge into the structures of the Central Indian Ridge, is considered the youngest.

Spreading ridges divide the ocean floor into three sectors - African in the west, Asian-Australian in the northeast and Antarctic in the south. Within the sectors there are intra-oceanic uplifts of various natures, represented by “aseismic” ridges, plateaus and islands. Tectonic (block) uplifts have a block structure with varying crustal thickness; often include continental remains. Volcanic uplifts are mainly associated with fault zones. The uplifts are the natural boundaries of deep-sea basins. African sector characterized by the predominance of fragments of continental structures (including microcontinents), within which the thickness of the earth's crust reaches 17–40 km (Agullas and Mozambique plateaus, the Madagascar ridge with the island of Madagascar, individual blocks of the Mascarene ridge with the Bank of the Seychelles Islands and the Saya de Bank -Malya). Volcanic uplifts and structures include the Comoros underwater ridge, crowned with archipelagos of coral and volcanic islands, Amirant Range, Reunion Islands, Mauritius, Tromelin, Farquhar Massif. In the western part of the African sector I. o. (western part of the Somali Basin, northern part of the Mozambique Basin), adjacent to the eastern underwater margin of Africa, the age of the earth’s crust is predominantly Late Jurassic-Early Cretaceous; in the central part of the sector (Mascarene and Madagascar basins) – Late Cretaceous; in the northeastern part of the sector (eastern part of the Somali Basin) – Paleocene-Eocene. Ancient spreading axes and transform faults intersecting them have been identified in the Somali and Mascarene basins.

For the northwestern (Asian) part Asian-Australian sector characterized by meridional “aseismic” ridges of block structure with increased thickness of the oceanic crust, the formation of which is associated with a system of ancient transform faults. These include the Maldives range, crowned by archipelagos of coral islands - Laccadive, Maldives and Chagos; so-called ridge 79°, Lanka ridge with Mount Afanasia Nikitin, East Indian (so-called ridge 90°), Investigator, etc. Thick (8–10 km) sediments of the Indus, Ganges and Brahmaputra rivers in the northern part of the I.O. partially overlapped by ridges extending in this direction, as well as by the structures of the transition zone between the Indian Ocean and the southeastern edge of Asia. The Murray Ridge in the northern part of the Arabian Basin, bounding the Oman Basin from the south, is a continuation of folded land structures; falls within the Owen fault zone. South of the equator, a sublatitudinal zone of intraplate deformations up to 1000 km wide has been identified, which is characterized by high seismicity. It stretches in the Central and Cocos Basins from the Maldives Ridge to the Sunda Trench. The Arabian Basin is underlain by crust of Paleocene-Eocene age, the Central Basin by crust of Late Cretaceous - Eocene age; the crust is youngest in the southern part of the basins. In the Cocos Basin, the crust ranges in age from Late Cretaceous in the south to Eocene in the north; in its northwestern part, an ancient spreading axis was established, which separated the Indian and Australian lithospheric plates until the mid-Eocene. The Coconut Rise, a latitudinal uplift with numerous seamounts and islands (including the Cocos Islands) rising above it, and the Rhu Rise, adjacent to the Sunda Trench, separate the southeastern (Australian) part of the Asian-Australian sector. Western Australian Basin (Wharton) in the central part of the Asian-Australian sector of the I.O. it is underlain by Late Cretaceous crust in the north-west and Late Jurassic in the east. Submerged continental blocks (marginal plateaus of Exmouth, Cuvier, Zenith, Naturalista) divide the eastern part of the basin into separate depressions - Cuvier (north of the Cuvier plateau), Perth (north of the Naturalista plateau). The crust of the North Australian Basin (Argo) is the oldest in the south (Late Jurassic); becomes younger in a northern direction (until the Early Cretaceous). The age of the crust of the South Australian Basin is Late Cretaceous – Eocene. The Brocken Plateau (West Australian Ridge) is an intra-oceanic rise with increased (from 12 to 20 km, according to various sources) crustal thickness.

IN Antarctic sector And about. There are mainly volcanic intra-oceanic uplifts with increased thickness of the earth's crust: the Kerguelen, Crozet (Del Caño) and Conrad plateaus. Within the largest Kerguelen plateau, presumably founded on an ancient transform fault, the thickness of the earth’s crust (according to some data, Early Cretaceous age) reaches 23 km. Rising above the plateau, the Kerguelen Islands are a multiphase volcanoplutonic structure (composed of alkali basalts and syenites of Neogene age). On Heard Island there are Neogene-Quaternary alkaline volcanics. In the western part of the sector there are the Conrad plateau with the volcanic mountains Ob and Lena, as well as the Crozet plateau with a group of volcanic islands Marion, Prince Edward, Crozet, composed of Quaternary basalts and intrusive massifs of syenites and monzonites. The age of the earth's crust within the African-Antarctic, Australian-Antarctic basins and the Crozet Basin of the Late Cretaceous is Eocene.

For I. o. in general, the predominance of passive margins is characteristic (the continental margins of Africa, the Arabian and Indian peninsulas, Australia, Antarctica). The active margin is observed in the northeastern part of the ocean (the Sunda transition zone between the Indian Ocean and Southeast Asia), where subduction(underthrust) of the ocean lithosphere under the Sunda island arc. A subduction zone of limited extent, the Makran subduction zone, was identified in the northwestern part of the I.O. Along the Agulhas I. plateau. borders the African continent along a transform fault.

Formation of the I. o. began in the middle of the Mesozoic during the split of the Gondwanan part (see. Gondwana) supercontinent Pangea, which was preceded by continental rifting during the Late Triassic - Early Cretaceous. The formation of the first sections of oceanic crust as a result of the separation of continental plates began in the Late Jurassic in the Somali (about 155 million years ago) and North Australian (151 million years ago) basins. In the Late Cretaceous, the northern part of the Mozambique Basin experienced the spreading of the bottom and the new formation of oceanic crust (140–127 million years ago). The separation of Australia from Hindustan and Antarctica, accompanied by the opening of basins with oceanic crust, began in the Early Cretaceous (about 134 million years ago and about 125 million years ago, respectively). Thus, in the Early Cretaceous (about 120 million years ago), narrow oceanic basins arose, cutting into the supercontinent and dividing it into separate blocks. In the middle of the Cretaceous period (about 100 million years ago), the ocean floor began to grow intensively between Hindustan and Antarctica, which led to the drift of Hindustan in a northerly direction. In the time interval of 120–85 million years ago, the spreading axes that existed north and west of Australia, off the coast of Antarctica and in the Mozambique Channel, died out. In the Late Cretaceous (90–85 million years ago), a split began between Hindustan with the Mascarene-Seychelles block and Madagascar, which was accompanied by bottom spreading in the Mascarene, Madagascar and Crozet basins, as well as the formation of the Australasian-Antarctic Rise. At the Cretaceous-Paleogene boundary, Hindustan separated from the Mascarene-Seychelles block; the Arabian-Indian spreading ridge arose; the extinction of spreading axes occurred in the Mascarene and Madagascar basins. In the middle of the Eocene, the Indian lithospheric plate merged with the Australian one; the still developing system of mid-ocean ridges was formed. Close to the modern appearance of the I. o. acquired in the early-mid Miocene. In the middle of the Miocene (about 15 million years ago), during the split of the Arabian and African plates, new formation of oceanic crust began in the Gulf of Aden and the Red Sea.

Modern tectonic movements in the I. o. noted in mid-ocean ridges (associated with shallow-focus earthquakes), as well as in individual transform faults. The area of ​​intense seismicity is the Sunda island arc, where deep-focus earthquakes are caused by the presence of a seismofocal zone plunging in the northeast direction. During earthquakes on the northeastern outskirts of the I. o. tsunami formation is possible.

Bottom sediments

The rate of sedimentation in the I. region. generally lower than in the Atlantic and Pacific oceans. The thickness of modern bottom sediments varies from a discontinuous distribution at mid-ocean ridges to several hundred meters in deep-sea basins and 5000–8000 m at the foot of continental slopes. The most widespread are calcareous (mainly foraminiferal-coccolithic) silts, covering over 50% of the ocean floor area (on continental slopes, ridges and the bottom of basins at depths of up to 4700 m) in warm oceanic areas from 20° N. w. up to 40° south w. with high biological productivity of water. Polygenic sediments – red deep ocean clays– occupy 25% of the bottom area at depths of over 4700 m in the eastern and southeastern parts of the ocean from 10° N. w. up to 40° south w. and in areas of the bottom remote from islands and continents; in the tropical region, red clays alternate with siliceous radiolarian silts covering the bottom of deep-sea basins of the equatorial belt. In deep-sea sediments, they are present in the form of inclusions. ferromanganese nodules. Siliceous, predominantly diatomaceous, silts occupy about 20% of the bottom of the I. lake; distributed at great depths south of 50° S. w. The accumulation of terrigenous sediments (pebbles, gravel, sands, silts, clays) occurs mainly along the coasts of continents and within their underwater margins in areas of river and iceberg runoff and significant wind removal of material. The sediments covering the African shelf are mainly of shell and coral origin; phosphorite nodules are widely developed in the southern part. Along the northwestern periphery of the Indian Ocean, as well as in the Andaman Basin and the Sunda Trench, bottom sediments are represented mainly by deposits of turbidity (turbide) flows - turbidites with the participation of products of volcanic activity, underwater landslides, landslides, etc. Sediments of coral reefs are widespread in the western part of the island. from 20° south w. up to 15° N. latitude, and in the Red Sea - up to 30° N. w. IN rift valley Red Sea outlets discovered metalliferous brines with temperatures up to 70 °C and salinity up to 300‰. IN metalliferous sediments, formed from these brines, have a high content of non-ferrous and rare metals. On continental slopes, seamounts, and mid-ocean ridges, there are outcrops of bedrock (basalts, serpentinites, peridotites). Bottom sediments around Antarctica are distinguished into a special type of iceberg deposits. They are characterized by a predominance of a variety of clastic material, ranging from large boulders to silts and fine silts.

Climate

Unlike the Atlantic and Pacific oceans, which have a meridional extension from the shores of Antarctica to the Arctic Circle and communicate with the Arctic Ocean, the I. o. in the northern tropical region it is bordered by a land mass, which largely determines the characteristics of its climate. The uneven heating of land and ocean leads to seasonal changes in extensive minimums and maximums of atmospheric pressure and to seasonal shifts of the tropical atmospheric front, which in the winter of the Northern Hemisphere retreats south to almost 10° S. sh., and in summer it is located in the foothills of southern Asia. As a result, over the northern part of the I. region. The climate is dominated by a monsoon climate, which is primarily characterized by changes in wind direction throughout the year. The winter monsoon with relatively weak (3–4 m/s) and stable northeast winds operates from November to March. During this period, north of 10° S. w. Calms are common. The summer monsoon with southwest winds occurs from May to September. In the northern tropical region and in the equatorial zone of the ocean, the average wind speed reaches 8–9 m/s, often reaching storm force. In April and October, a restructuring of the pressure field usually occurs, and during these months the wind situation is unstable. Against the background of the prevailing monsoon atmospheric circulation over the northern part of the I. region. isolated manifestations of cyclonic activity are possible. During the winter monsoon, there are known cases of cyclones developing over the Arabian Sea, and during the summer monsoon - over the waters of the Arabian Sea and the Bay of Bengal. Strong cyclones in these areas sometimes form during periods of monsoon change.

Approximately 30° S. w. in the central part of I. o. there is a stable area of ​​high pressure, the so-called. South Indian High. This stationary anticyclone, part of the southern subtropical high pressure area, persists throughout the year. The pressure at its center varies from 1024 hPa in July to 1020 hPa in January. Under the influence of this anticyclone in the latitudinal band between 10 and 30° S. w. Steady southeast trade winds blow throughout the year.

South of 40° S. w. atmospheric pressure in all seasons decreases uniformly from 1018–1016 hPa on the southern periphery of the South Indian High to 988 hPa at 60° S. w. Under the influence of the meridional pressure gradient in the lower layer of the atmosphere, a stable zap is maintained. air transfer. The highest average wind speed (up to 15 m/s) is observed in the middle of winter in the Southern Hemisphere. For higher southern latitudes I. o. Throughout almost the entire year, stormy conditions are characteristic, in which winds with speeds of more than 15 m/s, causing waves over 5 m in height, have a frequency of 30%. South of 60° S. w. Along the coast of Antarctica, easterly winds and two or three cyclones per year are usually observed, most often in July–August.

In July, the highest air temperatures in the surface layer of the atmosphere are observed at the top of the Persian Gulf (up to 34 °C), the lowest are off the coast of Antarctica (–20 °C), over the Arabian Sea and the Bay of Bengal on average 26–28 °C. Above the water area of ​​the I. o. air temperature almost everywhere changes in accordance with geographic latitude. In the southern part of I. o. it gradually decreases from north to south by about 1 °C every 150 km. In January, the highest air temperatures (26–28 °C) are observed in the equatorial belt, near the northern coasts of the Arabian Sea and the Bay of Bengal - about 20 °C. In the southern part of the ocean, the temperature gradually decreases from 26 °C in the Southern Tropics to 0 °C and slightly lower at the latitude of the Antarctic Circle. The amplitude of annual fluctuations in air temperature over b. parts of the water area of ​​the I. o. on average less than 10 °C and only off the coast of Antarctica increases to 16 °C.

The greatest amount of precipitation per year falls in the Bay of Bengal (over 5500 mm) and eastern shores islands of Madagascar (more than 3500 mm). The northern coastal part of the Arabian Sea receives the least amount of rainfall (100–200 mm per year).

North-eastern regions of I. o. located in seismically active areas. The eastern coast of Africa and the island of Madagascar, the shores of the Arabian Peninsula and the Hindustan Peninsula, almost all island archipelagos of volcanic origin, western shores Australia, especially the Sunda Islands arc, has in the past been repeatedly exposed to tsunami waves of varying strength, up to catastrophic ones. In 1883, after the explosion of the Krakatau volcano in the Jakarta area, a tsunami with a wave height of over 30 m was recorded; in 2004, a tsunami caused by an earthquake in the area of ​​​​the island of Sumatra had catastrophic consequences.

Hydrological regime

Seasonality in changes in hydrological characteristics (primarily temperature and currents) is most clearly manifested in the northern part of the ocean. The summer hydrological season here corresponds to the duration of the southwest monsoon (May - September), the winter - to the northeast monsoon (November - March). A feature of the seasonal variability of the hydrological regime is that the restructuring of hydrological fields is somewhat delayed relative to the meteorological fields.

Water temperature. In the winter of the Northern Hemisphere, the highest water temperatures in the surface layer are observed in the equatorial zone - from 27 °C off the coast of Africa to 29 °C or more east of the Maldives. In the northern regions of the Arabian Sea and Bay of Bengal, the water temperature is about 25 °C. In the southern part of I. o. Everywhere there is a zonal distribution of temperature, which gradually decreases from 27–28 °C to 20° S. w. to negative values ​​at the edge of the drifting ice, located approximately 65–67° S. w. In the summer season, the highest water temperatures in the surface layer are observed in the Persian Gulf (up to 34 °C), in the north-west of the Arabian Sea (up to 30 °C), in the eastern part of the equatorial zone (up to 29 °C). In the coastal areas of the Somali and Arabian peninsulas, abnormally low values ​​(sometimes less than 20 °C) are observed at this time of year, which is the result of the rise to the surface of cooled deep waters in the Somali Current system. In the southern part of I. o. The distribution of water temperature throughout the year remains zonal in nature, with the difference that its negative values ​​in the winter of the Southern Hemisphere are found much further north, already around 58–60° S. w. The amplitude of annual fluctuations in water temperature in the surface layer is small and averages 2–5 °C; only in the area of ​​the Somali coast and in the Gulf of Oman in the Arabian Sea does it exceed 7 °C. The water temperature quickly decreases vertically: at a depth of 250 m it almost everywhere drops below 15 °C, deeper than 1000 m – below 5 °C. At a depth of 2000 m, temperatures above 3 °C are observed only in the northern part of the Arabian Sea, in the central regions - about 2.5 °C, in the southern part it decreases from 2 °C to 50° S. w. to 0 °C off the coast of Antarctica. Temperatures in the deepest (over 5000 m) basins range from 1.25 °C to 0 °C.

Salinity of surface waters I. o. is determined by the balance between the amount of evaporation and the total amount of precipitation and river flow for each region. The absolute maximum salinity (over 40‰) is observed in the Red Sea and the Persian Gulf, in the Arabian Sea everywhere, with the exception of a small area in the southeastern part, salinity is above 35.5‰, in the band 20–40° S. w. – more than 35‰. The area of ​​low salinity is located in the Bay of Bengal and in the area adjacent to the Sunda Islands arc, where fresh river flow is high and precipitation is greatest. In the northern part of the Bay of Bengal, salinity is 30–31‰ in February, and 20‰ in August. An extensive tongue of water with salinity up to 34.5‰ at 10° south. w. extends from the island of Java to 75° east. e. In Antarctic waters, salinity is everywhere below the average oceanic value: from 33.5‰ in February to 34.0‰ in August, its changes are determined by slight salinization during the formation of sea ice and corresponding desalination during the melting of ice. Seasonal changes in salinity are noticeable only in the upper, 250-meter layer. With increasing depth, not only seasonal fluctuations fade, but also spatial variability of salinity; deeper than 1000 m it fluctuates between 35–34.5‰.

Density The highest density of water in I. o. observed in the Suez and Persian Gulfs (up to 1030 kg/m 3) and in cold Antarctic waters (1027 kg/m 3), average - in the warmest and saltiest waters in the northwest (1024–1024.5 kg/m 3) , the smallest is in the most desalinated waters in the northeastern part of the ocean and in the Bay of Bengal (1018–1022 kg/m3). With depth, mainly due to a decrease in water temperature, its density increases, sharply increasing in the so-called. jump layer, which is most noticeably expressed in the equatorial zone of the ocean.

Ice regime. Severity of climate in the southern part of the island. is such that the process of sea ice formation (at air temperatures below –7 °C) can occur almost all year round. The ice cover reaches its greatest development in September–October, when the width of the drifting ice belt reaches 550 km, and its smallest development in January–February. Ice cover is characterized by great seasonal variability and its formation occurs very quickly. The ice edge moves north at a speed of 5–7 km/day, and retreats just as quickly (up to 9 km/day) to the south during the melting period. Fast ice is established annually, reaches an average width of 25–40 km and almost completely melts by February. Drifting ice off the coast of the continent moves under the influence of katabatic winds in a general direction to the west and northwest. Near the northern edge, the ice drifts eastward. A characteristic feature of the Antarctic ice sheet is the large number of icebergs breaking off from the outlet and shelf glaciers of Antarctica. Table-shaped icebergs are especially large, which can reach a gigantic length of several tens of meters, rising 40–50 m above the water. Their number quickly decreases as they move away from the shores of the mainland. The average lifespan of large icebergs is 6 years.

Currents I. Circulation of surface waters in the northern part of the I. region. is formed under the influence of monsoon winds and therefore changes significantly from the summer to the winter season. In February from 8° N. w. off the Nicobar Islands to 2° N. w. off the coast of Africa there is a surface winter Monsoon current with speeds of 50–80 cm/s; with a core running approximately 18° S. sh., in the same direction the South Trade Wind Current is spreading, with an average speed on the surface of about 30 cm/s. Connecting off the coast of Africa, the waters of these two streams give rise to the Intertrade Countercurrent, which carries its waters to the east with velocities in the core of about 25 cm/s. Along the North African coast, with a general direction to the south, the waters of the Somali Current move, partially turning into the Intertrade Countercurrent, and to the south - the Mozambique and Cape Agulhas Currents, moving south at speeds of about 50 cm/s. Part of the South Trade Wind Current off the eastern coast of the island of Madagascar turns south along it (Madagascar Current). South of 40° S. w. the entire ocean area is crossed from west to east by the longest and most powerful stream in the World Ocean Western Wind Currents(Antarctic Circumpolar Current). The velocities in its rods reach 50 cm/s, and the flow rate is about 150 million m 3 /s. At 100–110° E. from it a stream branches off, heading north and giving rise to the Western Australian Current. In August, the Somali Current follows a general direction to the northeast and, at a speed of up to 150 cm/s, pushes water into the northern part of the Arabian Sea, from where the Monsoon Current, skirting the western and southern shores of the Hindustan Peninsula and the island of Sri Lanka, carries water to the shores of the island Sumatra turns south and merges with the waters of the South Trade Wind Current. Thus, in the northern part of I. o. an extensive clockwise gyre is created, consisting of the Monsoon, South Trade Wind and Somali Currents. In the southern part of the ocean, the pattern of currents changes little from February to August. Off the coast of Antarctica, in a narrow coastal strip, a current caused by katabatic winds and directed from east to west is observed all year round.

Water masses. In the vertical structure of water masses I. o. According to hydrological characteristics and depth, surface, intermediate, deep and bottom waters are distinguished. Surface waters are distributed in a relatively thin surface layer and, on average, occupy the upper 200–300 m. From north to south, water masses are distinguished in this layer: Persian and Arabian in the Arabian Sea, Bengal and South Bengal in the Bay of Bengal; further, south of the equator - Equatorial, Tropical, Subtropical, Subantarctic and Antarctic. As the depth increases, the differences between neighboring water masses decrease and their number decreases accordingly. Thus, in intermediate waters, the lower limit of which reaches 2000 m in temperate and low latitudes and up to 1000 m in high latitudes, the Persian and Red Sea in the Arabian Sea, the Bengal in the Bay of Bengal, the Subantarctic and Antarctic intermediate water masses are distinguished. Deep waters are represented by the North Indian, Atlantic (in the western part of the ocean), Central Indian (in the eastern part) and Circumpolar Antarctic water masses. Bottom waters everywhere, except the Bay of Bengal, are represented by one Antarctic bottom water mass, filling all deep-sea basins. The upper limit of bottom water is located on average at a horizon of 2500 m off the coast of Antarctica, where it is formed, up to 4000 m in the central regions of the ocean and rises to almost 3000 m north of the equator.

Tides and waves e. The greatest distribution on the shores of the I. o. have semidiurnal and irregular semidiurnal tides. Semidiurnal tides are observed on the African coast south of the equator, in the Red Sea, off the northwestern coast of the Persian Gulf, in the Bay of Bengal, and off the northwestern coast of Australia. Irregular semidiurnal tides - off the Somali Peninsula, in the Gulf of Aden, off the coast of the Arabian Sea, in the Persian Gulf, off the southwestern coast of the Sunda island arc. Diurnal and irregular tides occur off the western and southern coasts of Australia. The highest tides are off the northwestern coast of Australia (up to 11.4 m), in the mouth of the Indus (8.4 m), in the mouth of the Ganges (5.9 m), off the coast of the Mozambique Strait (5.2 m) ; in the open ocean, the magnitude of the tides varies from 0.4 m near the Maldives to 2.0 m in the southeastern part of the island. Waves reach their greatest strength in temperate latitudes in the zone of action of westerly winds, where the frequency of waves over 6 m high per year is 17%. Waves with a height of 15 m and a length of 250 m were recorded near the Kerguelen Island, and 11 m and 400 m, respectively, off the coast of Australia.

Flora and fauna

The main part of the water area of ​​the I. o. located within the tropical and southern temperate zones. Absence in I. o. northern high-latitude region and the action of monsoons lead to two differently directed processes that determine the characteristics of the local flora and fauna. The first factor complicates deep-sea convection, which negatively affects the renewal of deep waters of the northern part of the ocean and the increase in oxygen deficiency in them, which is especially pronounced in the Red Sea intermediate water mass, which leads to a depletion of species composition and reduces the total biomass of zooplankton in the intermediate layers. When oxygen-poor waters in the Arabian Sea reach the shelf, local death occurs (death of hundreds of thousands of tons of fish). At the same time, the second factor (monsoons) creates favorable conditions for high biological productivity in coastal areas. Under the influence of the summer monsoon, water is driven along the Somali and Arabian coasts, which causes powerful upwelling, bringing water rich in nutritious salts to the surface. The winter monsoon, although to a lesser extent, leads to seasonal upwelling with similar consequences off the western coast of the Indian subcontinent.

The coastal zone of the ocean has the greatest species diversity. The shallow waters of the tropical zone are characterized by numerous 6- and 8-rayed madrepore corals and hydrocorals that, together with red algae, can create underwater reefs and atolls. Among the powerful coral structures lives a rich fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, brittle stars and starfish), small but brightly colored coral reef fish. Most of the coasts are occupied by mangroves. At the same time, the fauna and flora of beaches and rocks that dry out at low tide are quantitatively depleted due to the depressing effect of sunlight. In the temperate zone, life on such sections of the coast is much richer; Dense thickets of red and brown algae (kelp, fucus, macrocystis) develop here, and a variety of invertebrates are abundant. According to L.A. Zenkevich(1965), St. 99% of all species of bottom and benthic animals living in the ocean live in the littoral and sublittoral zones.

The open spaces of the lake, especially the surface layer, are also characterized by rich flora. The food chain in the ocean begins with microscopic single-celled plant organisms - phytoplankton, which inhabit mainly the uppermost (about 100-meter) layer of ocean waters. Among them, several species of peridinian and diatom algae predominate, and in the Arabian Sea - cyanobacteria (blue-green algae), which often cause the so-called mass development. water bloom. In the northern part of I. o. There are three areas of highest phytoplankton production: the Arabian Sea, Bay of Bengal and Andaman Sea. The greatest production is observed off the coast of the Arabian Peninsula, where the number of phytoplankton sometimes exceeds 1 million cells/l (cells per liter). Its high concentrations are also observed in the subantarctic and Antarctic zones, where during the spring flowering period there are up to 300,000 cells/l. The lowest phytoplankton production (less than 100 cells/l) is observed in the central part of the ocean between parallels 18 and 38° S. w.

Zooplankton inhabits almost the entire thickness of oceanic waters, but its quantity quickly decreases with increasing depth and decreases by 2–3 orders of magnitude toward the bottom layers. Food for b. Some of the zooplankton, especially those living in the upper layers, are phytoplankton, therefore the patterns of spatial distribution of phyto- and zooplankton are largely similar. The highest levels of zooplankton biomass (from 100 to 200 mg/m3) are observed in the Arabian and Andaman seas, the Bengal, Aden and Persian Gulfs. The main biomass of ocean animals consists of copepod crustaceans (more than 100 species), with slightly less pteropods, jellyfish, siphonophores and other invertebrate animals. Radiolarians are typical of unicellular organisms. In the Antarctic region I. o. characterized by a huge number of euphausian crustaceans of several species, collectively called “krill”. Euphausiids create the main food supply for the largest animals on Earth - baleen whales. In addition, fish, seals, cephalopods, penguins and other bird species feed on krill.

Organisms that move freely in the marine environment (nekton) are presented in the I. o. mainly fish, cephalopods, and cetaceans. From cephalopods in I. o. Cuttlefish, numerous squid and octopuses are common. Of the fish, the most abundant are several species of flying fish, luminous anchovies (coryphaenas), sardinella, sardine, mackerel, nototheniids, groupers, several types of tuna, blue marlin, grenadier, sharks, and rays. Warm waters are home to sea turtles and poisonous sea snakes. The fauna of aquatic mammals is represented by various cetaceans. The most common baleen whales are: blue whale, sei whale, fin whale, humpback whale, and Australian (Cape) whale. Toothed whales are represented by sperm whales and several species of dolphins (including killer whales). In the coastal waters of the southern part of the ocean, pinnipeds are widespread: the Weddell seal, the crabeater seal, seals - Australian, Tasmanian, Kerguelen and South African, Australian sea lion, leopard seal, etc. Among the birds, the most typical are the wandering albatross, petrels, great frigatebird, phaetons , cormorants, gannets, skuas, terns, gulls. South of 35° S. sh., on the coasts of South Africa, Antarctica and islands - numerous. colonies of several penguin species.

In 1938 in I. o. a unique biological phenomenon was discovered - a living lobe-finned fish Latimeria chalumnae, considered extinct tens of millions of years ago. "Fossil" coelacanth lives at a depth of over 200 m in two places - near Comoros and in the waters of the Indonesian archipelago.

History of the study

The northern coastal areas, especially the Red Sea and deeply incised bays, began to be used by humans for navigation and fishing already in the era of ancient civilizations, several thousand years BC. e. 600 BC e. Phoenician sailors who were in the service of Egyptian pharaoh Necho II, circumnavigated Africa. In 325–324 BC. e. Alexander the Great's comrade Nearchus, commanding a fleet, sailed from India to Mesopotamia and compiled the first descriptions of the coastline from the mouth of the Indus River to the top of the Persian Gulf. In the 8th–9th centuries. The Arabian Sea was intensively developed Arab sailors, who created the first sailing directions and navigation guides for this area. In the 1st half. 15th century Chinese navigators under the leadership of Admiral Zheng He made a series of voyages along the Asian coast to the west, reaching the coast of Africa. In 1497–99 the Portuguese Vasco da Gama paved for Europeans sea ​​route to India and the countries of Southeast Asia. A few years later, the Portuguese discovered the island of Madagascar, the Amirante, Comoros, Mascarene and Seychelles islands. Following the Portuguese in I. o. The Dutch, French, Spanish and English entered. The name "Indian Ocean" first appeared on European maps in 1555. In 1772–75 J. Cook penetrated into I. o. to 71° 10" S and carried out the first deep-sea measurements. Oceanographic research on the island began with systematic measurements of water temperature during circumnavigation of the world Russian ships "Rurik" (1815–18) and "Enterprise" (1823–26). In 1831–36, an English expedition took place on the ship Beagle, on which Charles Darwin carried out geological and biological work. Complex oceanographic measurements in the I. o. were carried out during the English expedition on the Challenger ship in 1873–74. Oceanographic work in the northern part of the island. performed in 1886 by S. O. Makarov on the ship “Vityaz”. In the 1st half. 20th century oceanographic observations began to be carried out regularly, and by the 1950s. they were conducted at almost 1,500 deep-sea oceanographic stations. In 1935, P. G. Schott’s monograph “Geography of the Indian and Pacific Oceans” was published - the first major publication that summarized the results of all previous studies in this region. In 1959, the Russian oceanographer A. M. Muromtsev published a fundamental work - “The Main Features of the Hydrology of the Indian Ocean.” In 1960–65, the Scientific Committee on Oceanography of UNESCO conducted the International Indian Ocean Expedition (IIOE), the largest of those previously operating in the Indian Ocean. Scientists from more than 20 countries of the world (USSR, Australia, Great Britain, India, Indonesia, Pakistan, Portugal, USA, France, Germany, Japan, etc.) took part in the MIOE program. During the MIOE, major geographical discoveries were made: the underwater West Indian and East Indian ridges were discovered, tectonic fault zones - Owen, Mozambique, Tasmanian, Diamantina, etc., underwater mountains - Ob, Lena, Afanasia Nikitina, Bardina, Zenit, Equator and etc., deep-sea trenches - Ob, Chagos, Vima, Vityaz, etc. In the history of the study of I. o. The results of research carried out in 1959–77 AD are particularly highlighted. the ship "Vityaz" (10 voyages) and dozens of other Soviet expeditions on ships of the Hydrometeorological Service and the State Fisheries Committee. From the beginning 1980s Ocean research was carried out within the framework of 20 international projects. Research on I. o. has become especially intensified. during the International Ocean Circulation Experiment (WOCE). After its successful completion in the end. 1990s the volume of modern oceanographic information on the I.O. doubled in size.

Modern research on I. o. are carried out within the framework of international programs and projects, such as the International Geosphere-Biosphere Program (since 1986, 77 countries participate), including the projects Dynamics of Global Ocean Ecosystems (GLOBES, 1995–2010), Global Flows of Matter in the Ocean ( JGOFS, 1988-2003), Land-Ocean Interactions in the Coastal Zone (LOICZ), Integrated Marine Biogeochemistry and Ecosystem Research (IMBER), Land-Ocean Interactions in the Coastal Zone (LOICZ, 1993-2015), Study of Ocean Surface Interactions with the lower atmosphere (SOLAS, 2004–15, ongoing); “World Climate Research Program” (WCRP, since 1980, 50 countries participate), the main marine part of which is the program “Climate and Ocean: Instability, Predictability and Variability” (CLIVAR, since 1995), the basis of which was the results of TOGA and WOCE; International study of biogeochemical cycles and large-scale distribution of trace elements and their isotopes in the marine environment (GEOTRACES, 2006–15, ongoing) and many others. etc. The Global Ocean Observing System (GOOS) is being developed. Since 2005, the international ARGO program has been operating, in which observations are carried out by autonomous sounding instruments throughout the World Ocean (including the Arctic Ocean), and the results are transmitted through artificial Earth satellites to data centers. From the end 2015 begins the 2nd International Indian Ocean Expedition, designed for 5 years of research with the participation of many countries.

Economic use

Coastal zone I. o. has an exceptionally high population density. There are over 35 states on the coasts and islands, home to about 2.5 billion people. (over 30% of the world's population). The bulk of the coastal population is concentrated in South Asia (more than 10 cities with a population of over 1 million people). In most countries in the region, there are acute problems of finding living space, creating jobs, providing food, clothing and housing, and medical care.

The use of the ocean, like other seas and oceans, is carried out in several main areas: transport, fishing, extraction of mineral resources, and recreation.

Transport

Role of acting in maritime transport increased significantly with the creation of the Suez Canal (1869), which opened a short sea route for communication with states washed by the waters of the Atlantic Ocean. is an area of ​​transit and export of all kinds of raw materials, in which almost all large sea ​​ports are of international importance. In the northeastern part of the ocean (in the Malacca and Sunda Straits) there are routes for ships traveling to the Pacific Ocean and back. Main export item to the USA, Japan and other countries Western Europe– crude oil from the Persian Gulf region. In addition, agricultural products are exported - natural rubber, cotton, coffee, tea, tobacco, fruits, nuts, rice, wool; wood; miner raw materials - coal, iron ore, nickel, manganese, antimony, bauxite, etc.; machinery, equipment, tools and metal products, chemical and pharmaceutical products, textile products, processed gems and jewelry. To the share of I. o. accounts for about 10% of the cargo turnover of world shipping, in con. 20th century About 0.5 billion tons of cargo were transported through its waters per year (according to IOC data). According to these indicators, it ranks 3rd after the Atlantic and Pacific oceans, inferior to them in terms of shipping intensity and total volumes cargo transportation, but surpassing all other sea transport communications in terms of oil transportation volume. The main transport routes along the Indian Ocean are directed to the Suez Canal, the Strait of Malacca, the southern tips of Africa and Australia, and along the northern coast. Shipping is most intense in the northern regions, although limited by storm conditions during the summer monsoon, and less intense in the central and southern regions. The growth of oil production in the Persian Gulf countries, Australia, Indonesia, and other places contributed to the construction and modernization of oil ports and the emergence of the I.O. giant tankers. The most developed transport routes for the transportation of oil, gas and petroleum products: Persian Gulf - Red Sea - Suez Canal - Atlantic Ocean; Persian Gulf – Strait of Malacca – Pacific Ocean; Persian Gulf - southern tip of Africa - Atlantic Ocean (especially before the reconstruction of the Suez Canal, 1981); Persian Gulf - Australian coast (port of Fremantle). Mineral and agricultural raw materials, textiles, precious stones, jewelry, equipment, and computer equipment are transported from India, Indonesia, and Thailand. From Australia, coal, gold, aluminum, alumina, iron ore, diamonds, uranium ores and concentrates, manganese, lead, zinc are transported; wool, wheat, meat products, as well as internal combustion engines, cars, electrical products, river boats, glass products, rolled steel, etc. Counter-flows are dominated by industrial goods, automobiles, electronic equipment, etc. I.O. plays an important role in transport use. transport of passengers.

Fishing

Compared to other oceans, the I. o. has relatively low biological productivity; production of fish and other seafood accounts for 5–7% of the total world catch. Fishing and non-fishery fishing is concentrated mainly in the northern part of the ocean, and in the west it is twice as much as in the eastern part. The largest volumes of bioproduct production are observed in the Arabian Sea off the western coast of India and off the coast of Pakistan. Shrimp are harvested in the Persian and Bengal Bays, and lobsters are harvested off the east coast of Africa and on tropical islands. In open ocean areas in the tropical zone, tuna fishing is widely developed, carried out by countries with well-developed fishing fleets. In the Antarctic region, nototheniids, icefish and krill are caught.

Mineral resources

Almost throughout the entire shelf area of ​​the I. o. deposits of oil and natural combustible gas or oil and gas shows have been identified. The most industrially important are the actively developed oil and gas fields in the Persian Gulf ( Persian Gulf oil and gas basin), Suez (Gulf of Suez oil and gas basin), Cambay ( Cambay oil and gas basin), Bengali ( Bengal oil and gas basin); off the northern coast of the island of Sumatra (North Sumatra oil and gas basin), in the Timor Sea, off the northwestern coast of Australia (Carnarvon oil and gas basin), in Bass Strait (Gippsland oil and gas basin). Gas deposits have been explored in the Andaman Sea, oil and gas bearing areas in the Red Sea, Gulf of Aden, and along the coast of Africa. Coastal-sea placers of heavy sands are developed off the coast of the island of Mozambique, along the southwestern and northeastern coasts of India, off the northeastern coast of the island of Sri Lanka, along southwest coast Australia (mining of ilmenite, rutile, monazite and zircon); in the coastal areas of Indonesia, Malaysia, Thailand (cassiterite mining). On the shelves I. o. Industrial accumulations of phosphorites were discovered. Large fields of ferromanganese nodules, a promising source of Mn, Ni, Cu, and Co, have been established on the ocean floor. In the Red Sea, identified metal-bearing brines and sediments are potential sources of production of iron, manganese, copper, zinc, nickel, etc.; There are deposits of rock salt. In the coastal zone of the I. o. sand is mined for construction and glass production, gravel, and limestone.

Recreational resources

From the 2nd half. 20th century great importance for the economy of coastal countries has use recreational resources ocean. Old resorts are being developed and new ones are being built on the coasts of continents and on numerous tropical islands in the ocean. The most visited resorts are in Thailand (Phuket island, etc.) - over 13 million people. per year (together with the coast and islands of the Gulf of Thailand of the Pacific Ocean), in Egypt [Hurghada, Sharm el-Sheikh (Sharm el-Sheikh), etc.] - over 7 million people, in Indonesia (the islands of Bali, Bintan , Kalimantan, Sumatra, Java, etc.) - over 5 million people, in India (Goa, etc.), in Jordan (Aqaba), in Israel (Eilat), in the Maldives, in Sri Lanka, in the Seychelles islands, on the islands of Mauritius, Madagascar, South Africa, etc.

Port cities

On the banks of I. o. specialized oil loading ports are located: Ras Tanura ( Saudi Arabia), Kharq (Iran), Ash-Shuaiba (Kuwait). The largest ports of the island: Port Elizabeth, Durban (South Africa), Mombasa (Kenya), Dar es Salaam (Tanzania), Mogadishu (Somalia), Aden (Yemen), Kuwait City (Kuwait), Karachi (Pakistan) ), Mumbai, Chennai, Kolkata, Kandla (India), Chittagong (Bangladesh), Colombo (Sri Lanka), Yangon (Myanmar), Fremantle, Adelaide and Melbourne (Australia).