area 73 426 000 km²/28 350 000 sq mi. Third largest ocean in the world, bounded W by Africa, N by Asia, E by Australia and the Malay archipelago, and S by the Southern Ocean; width c.6400 km/4000 mi at the Equator; maximum depth of 7125 m/23 375 ft in the Java Trench; linked to the Mediterranean by the Suez Canal; floor divided into E and W sections by the Mid-Oceanic Ridge; rift valley runs along ridge axis, centre of sea-floor spreading; main island groups, Andaman, Nicobar, Chagos, Seychelles; largest islands, Madagascar and Sri Lanka.
| Earth's five oceans |
|---|
| Atlantic Ocean Arctic Ocean Indian Ocean Pacific Ocean Southern Ocean |
The Indian Ocean is the third largest body of water in the world, covering about 20% of the Earth's water surface. It is bounded on the north by Southern Asia (including the Indian subcontinent, hence its name); and on the south by the Southern Ocean. It is separated from the Atlantic Ocean by the 20° east meridian running south from Cape Agulhas, and from the Pacific by the 147° east meridian. The northernmost extent of the Indian Ocean is approximately 30° north latitude in the Persian Gulf. This ocean is nearly 10,000 kilometers (6,200 mi) wide at the southern tips of Africa and Australia;
The ocean's volume is estimated to be 292,131,000 cubic kilometers (70,086,000 mi3). Island nations within the ocean are Madagascar (formerly Malagasy Republic), the world's fourth largest island; The ocean's importance as a transit route between Asia and Africa has made it a scene of conflict. After World War II, the ocean has been dominated by India and Australia.
Geography
The African, Indian, and Antarctic crustal plates converge in the Indian Ocean. The ocean's continental shelves are narrow, averaging 200 kilometers (125 mi) in width. The average depth of the ocean is 3,890 meters (12,760 ft).
A spring 2000 decision by the International Hydrographic Organization delimited a fifth world ocean, stripping the southern portions of the Indian Ocean. The new ocean extends from the coast of Antarctica north to 60° south latitude which coincides with the Antarctic Treaty Limit. The Indian Ocean remains the third-largest of the world's five oceans.
Major chokepoints include Bab el Mandeb, Strait of Hormuz, Strait of Malacca, southern access to the Suez Canal, and the Lombok Strait. Seas include Andaman Sea, Arabian Sea, Bay of Bengal, Great Australian Bight, Gulf of Aden, Gulf of Oman, Laccadive Sea, Mozambique Channel, Persian Gulf, Red Sea, Strait of Malacca, and other tributary water bodies.
Climate
The climate north of the equator is affected by a monsoon wind system. In the Arabian Sea the violent monsoon brings rain to the Indian subcontinent.
Hydrology
Among the few large rivers flowing into the Indian Ocean are the Zambezi, Arvandrud/Shatt-al-Arab, Indus, Ganges, Brahmaputra, and Ayeyarwady River. Deepwater circulation is controlled primarily by inflows from the Atlantic Ocean, the Red Sea, and Antarctic currents. Surface water salinity ranges from 32 to 37 parts per 1000, the highest occurring in the Arabian Sea and in a belt between southern Africa and southwestern Australia.
Economy
The Indian Ocean provides major sea routes connecting the Middle East, Africa, and East Asia with Europe and the Americas. An estimated 40% of the world's offshore oil production comes from the Indian Ocean. Beach sands rich in heavy minerals, and offshore placer deposits are actively exploited by bordering countries, particularly India, South Africa, Indonesia, Sri Lanka, and Thailand.
The warmth of the Indian Ocean keeps phytoplankton production low, except along the northern fringes and in a few scattered spots elsewhere; life in the ocean is thus limited. Fishing fleets from Russia, Japan, South Korea, and Taiwan also exploit the Indian Ocean, mainly for shrimp and tuna.
Endangered marine species include the dugong, seals, turtles, and whales.
Oil pollution threatens the Arabian Sea, Persian Gulf, and Red Sea
History
The world's earliest civilizations in Mesopotamia (beginning with Sumer), ancient Egypt, and the Indian subcontinent (beginning with the Indus Valley civilization), which began along the valleys of the Tigris-Euphrates, Nile and Indus rivers respectively, had all developed around the Indian Ocean. 2500 BC) was conducted along the Indian Ocean.
The Indian Ocean is far calmer and thus opened to trade earlier than the Atlantic or Pacific Oceans. This allowed Indonesian peoples to cross the Indian Ocean to settle in Madagascar.
In the second or first century BC, Eudoxus of Cyzicus was the first Greek to cross the Indian Ocean. Like the Indonesian peoples above, the western sailors used the monsoon to cross the ocean.
From 1405 to 1433, Admiral Zheng He led a large fleet of the Ming Dynasty to the Western Ocean (Chinese name for the Indian Ocean) and reached the coastal country of East Africa.
In 1497, Vasco da Gama rounded the Cape of Good Hope, and became the first European to sail to India. The Dutch East India Company (1602-1798) sought control of trade with the East across the Indian Ocean.
The opening of the Suez Canal in 1869 revived European interest in the East, but no nation was successful in establishing trade dominance. Developing countries bordering the ocean, however, seek to have it made a "zone of peace" so that they may use its shipping lanes freely, though the United Kingdom and United States maintain a military base on Diego Garcia atoll in the middle of the Indian Ocean.
On December 26, 2004, the countries surrounding the Indian Ocean were hit by a tsunami caused by the 2004 Indian Ocean earthquake.
Major ports and harbors
Calcutta, India Chennai, India Colombo, Sri Lanka Durban, South Africa Jakarta, Indonesia Karachi, Pakistan Fremantle, Western Australia Geraldton, Western Australia Kismaayo, Somalia Mangalore, India Mombasa, Kenya Mumbai, India Pondicherry, India Richards Bay, South Africa Visakhapatnam, India Kochi, India Goa, India Watamu, Kenya Male, MaldivesPort of Somalia, Somalia
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