Indian Ocean Geography

excerpted from: THE WORLD FACTBOOK 1994, ELECTRONIC VERSION produced by the Central Intelligence Agency.


Location: body of water between Africa, Asia, Australia, and Antarctica

Map references: Southeast Asia, Standard Time Zones of the World

total area 73.6 million sq km
comparative area slightly less than eight times the size of the US; third-largest ocean (after the Pacific Ocean and Atlantic Ocean, but larger than the Arctic Ocean)
note includes Arabian Sea, Bay of Bengal, Persian Gulf, Red Sea, Strait of Malacca, Great Australian Bight, Gulf of Oman, Mozambique Channel, and other tributary water bodies

Coastline: 66,526 km

International disputes: some maritime disputes (see littoral states)

Climate: northeast monsoon (December to April), southwest monsoon (June to October); tropical cyclones occur during May/June and October/November in the north Indian Ocean and January/February in the south Indian Ocean

Terrain: surface dominated by counterclockwise gyre (broad, circular system of currents) in the south Indian Ocean; unique reversal of surface currents in the north Indian Ocean, low atmospheric pressure over southwest Asia from hot, rising, summer air results in the southwest monsoon and southwest-to-northeast winds and currents, while high pressure over northern Asia from cold, falling, winter air results in the northeast monsoon and northeast-to-southwest winds and currents; ocean floor is dominated by the Mid-Indian Ocean Ridge and subdivided by the Southeast Indian Ocean Ridge, Southwest Indian Ocean Ridge, and Ninety East Ridge; maximum depth is 7,258 meters in the Java Trench

Natural resources: oil and gas fields, fish, shrimp, sand and gravel aggregates, placer deposits, polymetallic nodules

current issues endangered marine species include the dugong, seals, turtles, and whales; oil pollution in the Arabian Sea, Persian Gulf, and Red Sea
natural hazards NA
international agreements NA

Note: major chokepoints include Bab el Mandeb, Strait of Hormuz, Strait of Malacca, southern access to the Suez Canal, and the Lombok Strait; ships subject to superstructure icing in extreme south near Antarctica from May to October


Digraph: XO


Overview: The Indian Ocean provides major sea routes connecting the Middle East, Africa, and East Asia with Europe and the Americas. It carries a particularly heavy traffic of petroleum and petroleum products from the oil fields of the Persian Gulf and Indonesia. Its fish are of great and growing importance to the bordering countries for domestic consumption and export. Fishing fleets from Russia, Japan, Korea, and Taiwan also exploit the Indian Ocean, mainly for shrimp and tuna. Large reserves of hydrocarbons are being tapped in the offshore areas of Saudi Arabia, Iran, India, and Western Australia. 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.

Industries: based on exploitation of natural resources, particularly fish, minerals, oil and gas, fishing, sand and gravel


Ports: Bombay (India), Calcutta (India), Madras (India), Colombo (Sri Lanka), Durban (South Africa), Fremantle (Australia), Jakarta (Indonesia), Melbourne (Australia), Richards Bay (South Africa)

Telecommunications: submarine cables from India to United Arab Emirates and Malaysia, and from Sri Lanka to Djibouti and Indonesia

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gene carl feldman ( (301) 286-9428
Judith Gradwohl, Smithsonian Institution (Curator/Ocean Planet)