Indian Ocean - Region facts
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 (the Indian subcontinent); on the west by the Arabian Peninsula and Africa; on the east by the Malay Peninsula, the Sunda Islands, and Australia; and on the south by the Southern Ocean. It is separated from the Atlantic Ocean by the 20░east meridian south of Africa, 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 km (6,200 mi) wide at the southern tips of Africa and Australia; its area is 73,556,000 km▓ (28,400,000 mi▓), including the Red Sea and the Persian Gulf. The ocean's volume is estimated to be 292,131,000 km│ (70,086,000 mi│). Small islands dot the continental rims. Island nations within the ocean are Madagascar (formerly Malagasy Republic), the world's fourth largest island; Comoros; Seychelles; Maldives; Mauritius; and Sri Lanka. Indonesia borders it. The ocean's importance as a transit route between Asia and Africa has made it a scene of conflict. Because of its size, however, no one nation had successfully dominated until the early 1800s when Britain controlled much of the surrounding land.
Southern Ocean: 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.
total: 68.556 million km▓
seas: includes 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
Coastline: 66,526 km
Climate: northeast monsoon (December to April), southwest monsoon (June to October); tropical cyclones occur during May/June and October/November in the northern Indian Ocean and January/February in the southern Indian Ocean
Terrain: surface dominated by counterclockwise gyre (broad, circular system of currents) in the southern Indian Ocean; unique reversal of surface currents in the northern 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 Ninetyeast Ridge
Graphics of the seabed terrain produced by the Royal Navy & British Geological Survey in 2005 can be found here.
lowest point: Java Trench -7,258 m
highest point: sea level 0 m
Natural resources: oil and gas fields, fish, shrimp, sand and gravel aggregates, placer deposits, polymetallic nodules
Environment - current issues: endangered marine species include the dugong, seals, turtles, and whales; oil pollution in the Arabian Sea, Persian Gulf, and Red Sea
Geography - note: major chokepoints include Bab el Mandeb, Strait of Hormuz, Strait of Malacca, southern access to the Suez Canal, and the Lombok Strait
Ports and harbors: Calcutta (India), Chennai (Madras; India), Colombo (Sri Lanka), Durban (South Africa), Jakarta (Indonesia), Karachi (Pakistan), Fremantle (Australia), Mumbai (Bombay; India), Richards Bay (South Africa), Visakhapatnam (India),Kochi(India)
The earliest known civilizations, in the valleys of the Nile, Euphrates, Tigris, and Indus rivers and in Southeast Asia, have developed near the Indian Ocean. During Egypt's 1st dynasty (c. 3000 BCE), sailors were sent out onto its waters, journeying to Punt, thought to be part of present-day Somalia. Returning ships brought gold and Myrrh. Phoenicians of the 3rd millennium BCE may have entered the area, but no settlements resulted.
The Indian Ocean is far calmer and thus open to trade earlier than the Atlantic or Pacific. The powerful monsoons also meant ships could easily sail them west early in the season, then wait a few months and return eastwards. This allowed Indonesian peoples to cross the Indian Ocean to settle in Madagascar.
In the second or first century BCE Eudoxus of Cyzicus was the first Greek to cross the Indian Ocean. Hippalus is said to have discovered the direct route from Arabia to India around this time. During the first and second century CE intensive trade relations developed between Roman Egypt and the Tamil kingdoms of the Cheras, Cholas and Pandyas in Southern India. Like the Indonesian people above, the western sailors used the monsoon to cross the Ocean. The unknown author of the Periplus of the Erythraean Sea describes this route and the ports and trade goods along the coasts of Africa and India around 70 CE.
In 1497 Vasco da Gama rounded the Cape of Good Hope and sailed to India, the first European to do so. The European ships, armed with heavy cannon, quickly came to dominate the trade. Portugal at first attempted to achieve pre-eminence setting up forts at the important straits and ports. But the small nation was unable to support such a vast project and they were replaced in the mid-1600s by other European powers. The Dutch East India Company (1602-1798) sought control of trade with the East across the Indian Ocean. France and Britain established trade companies for the area. Eventually Britain became the principal power and by 1815 dominated the area.
The opening of the Suez Canal in 1869 revived European interest in the East, but no nation was successful in establishing trade dominance. Since World War II the United Kingdom has withdrawn from the area, to be only partially replaced by India, the USSR, and the United States. The last two have tried to establish hegemony by negotiating for naval base sites. 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 States did manage to salvage a naval base for itself at Deigo Garcia in the middle of the Indian Ocean.
On December 26, 2004 the countries surrounding the Indian Ocean were hit by tsunamis caused by the 2004 Indian Ocean earthquake. The waves resulted in more than 226,000 deaths and over 1 million homeless.
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 oilfields of the Persian Gulf and Indonesia. 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.
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 is confined to subsistence levels. Its fish are of great and growing importance to the bordering countries for domestic consumption and export. Fishing fleets from Russia, Japan, South Korea, and Taiwan also exploit the Indian Ocean, mainly for shrimp and tuna.