Indian Ocean

Indian Ocean

The Indian Ocean is the smallest of the three great oceans on earth. It lies between the continents of Asia, Africa, Australia and the Antarctic. It is almost 75 million km² in size. Its greatest depth is 7455 m in the Sunda Trench south of Java. The Indian Ocean is divided into eleven different deep-sea basins by a central system of ridges. In the Indian Ocean there are large islands such as Madagascar and Ceylon, and archipelagos such as the Seychelles and Maldives. Its location in the tropical and extra-tropical climates determines the climate and ocean currents. The main ocean currents are north and south equatorial currents and equatorial countercurrent. Systematic research into the Indian Ocean and its resources has been carried out since the end of the 19th century.

Location and size

The Indian Ocean is the smallest and geologically youngest of the three great oceans on earth. Sub seas are the Persian Gulf and the Red Sea. With the side seas it has a size of almost 75 million km². The Indian Ocean laps the coasts of the continents Asia, Africa, Australia and Antarctica. The Indian subcontinent divides the northern Indian Ocean into the Arabian Sea in the west and the Bay of Bengal in the east. The mean depth of the Indian Ocean is around 4000 m. It reaches its greatest depth in the Sunda Trench south of Java with 7455 m.


The Indian Ocean is divided into eleven deep-sea basins by a system of submarine ridges. In the center the ocean crosses from north to south the Arab-Indian and the central Indian ridges. The Central Indian Ridge forks east of Madagascar in a y-shape into two further ridges. In the eastern part of the Indic, the East Indian Ridge runs from the Andaman Islands off the coast of Rear India 4000 km to the south. There are many islands and archipelagos in the Indian Ocean. The largest islands are Madagascar off the southeast coast of Africa and Ceylon on the southern tip of India. Among the most famous archipelagos count the Comoros and Seychelles off Africa and the Maldives and Andamans off front and rear India.


The Indian Ocean ranges from the subtropical and tropical climatic zones in its northern and central parts to the temperate to the subpolar latitudes off the Antarctic coast. In the northern and central parts, the change from northeast monsoon in winter and southwest monsoon in summer are the climate-determining factors for the adjacent continents, for example the subcontinent India. In connection with the location, the water temperatures and the salinity of the Indian Ocean differ.

Ocean currents

As in the Atlantic and Pacific Oceans, there are also three warm, opposing ocean currents in the equatorial area of ​​the Indian Ocean: the north equatorial current, the south equatorial current and the equatorial countercurrent. During the summer monsoon, the strong Somali current forms off the East African coast.


The Indian Ocean is of little importance for fishing. Only around 5% of all fish caught in the world’s oceans come from this ocean. In addition, fishing is almost exclusively limited to areas near the coast. Above all, Japanese fishermen practice deep-sea fishing in the equatorial Indian Ocean.


In 1874, the British research ship “Challenger” began scientific research into the Indian Ocean. From 1959 to 1965, 40 research vessels from 20 countries took part in the Indian Ocean Expedition.

In 1979 the major project INDEX (Indian Ocean Experiment) was carried out as an international research project to investigate the causes and effects of the southwest monsoon. The Intergovernmental Oceanographic Commission (IOC) has been researching the western Indian Ocean
since 1982.

1988 The central and eastern countries bordering the Indian Ocean joined forces to explore the vast natural resources of this sea in more detail.

Indian Ocean

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