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Indian Ocean

2007 Schools Wikipedia Selection. Related subjects: General Geography

   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); 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 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; its area is 73,556,000 square kilometers
   (28,400,000 mi²), including the Red Sea and the Persian Gulf.

   The ocean's volume is estimated to be 292,131,000 cubic kilometers
   (70,086,000 mi^3). 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 nation had successfully
   dominated most of it until the early 1800s when Britain controlled much
   of the surrounding land. 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. Their junctures are marked by branches of the Mid-Oceanic
   Ridge forming an inverted Y, with the stem running south from the edge
   of the continental shelf near Mumbai, India. The eastern, western, and
   southern basins thus formed are subdivided into smaller basins by
   ridges. The ocean's continental shelves are narrow, averaging
   200 kilometers (125 mi) in width. An exception is found off Australia's
   western coast, where the shelf width exceeds 1,000 kilometers (600 mi).
   The average depth of the ocean is 3,890 meters (12,760 ft). Its deepest
   point, in the Java Trench, is estimated to be 7,450 meters (24,442 ft)
   below sea level. North of 50° south latitude, 86% of the main basin is
   covered by pelagic sediments, of which more than half is globigerina
   ooze. The remaining 14% is layered with terrigenous sediments. Glacial
   outwash dominates the extreme southern latitudes.

   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.
   Strong northeast winds blow from October until April; from May until
   October south and west winds prevail. In the Arabian Sea the violent
   monsoon brings rain to the Indian subcontinent. In the southern
   hemisphere the winds generally are milder, but summer storms near
   Mauritius can be severe. When the monsoon winds change, cyclones
   sometimes strike the shores of the Arabian Sea and the Bay of Bengal.

Hydrology

   Bathymetric map of the Indian Ocean
   Enlarge
   Bathymetric map of the Indian Ocean

   Among the few large rivers flowing into the Indian Ocean are the
   Zambezi, Arvandrud/Shatt-al-Arab, Indus, Ganges, Brahmaputra, and
   Ayeyarwady River. Currents are mainly controlled by the monsoon. Two
   large circular currents, one in the northern hemisphere flowing
   clockwise and one south of the equator moving counterclockwise,
   constitute the dominant flow pattern. During the winter monsoon,
   however, currents in the north are reversed. Deepwater circulation is
   controlled primarily by inflows from the Atlantic Ocean, the Red Sea,
   and Antarctic currents. North of 20° south latitude the minimum surface
   temperature is 22 °C (72 °F), exceeding 28 °C (82 °F) to the east.
   Southward of 40° south latitude, temperatures drop quickly. 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. Pack ice and icebergs are found throughout the
   year south of about 65° south latitude. The average northern limit of
   icebergs is 45° south latitude.

Economy

   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.

   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. Civilizations soon arose in Persia (beginning
   with Elam) and later in Southeast Asia (beginning with Funan). During
   Egypt's first dynasty (c. 3000 BC), sailors were sent out onto its
   waters, journeying to Punt, thought to be part of present-day Somalia.
   Returning ships brought gold and myrrh. The earliest known maritime
   trade between Mesopotamia and the Indus Valley (c. 2500 BC) was
   conducted along the Indian Ocean. Phoenicians of the late 3rd
   millennium BC may have entered the area, but no settlements resulted.

   The Indian Ocean is far calmer and thus opened to trade earlier than
   the Atlantic or Pacific Oceans. The powerful monsoons also meant ships
   could easily sail 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 BC, 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 centuries intensive trade relations developed between
   Roman Egypt and the Tamil kingdoms of the Cheras, Cholas and Pandyas in
   Southern India. Like the Indonesian peoples 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 AD.

   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 European ships, armed with heavy
   cannon, quickly dominated trade. Portugal at first attempted to achieve
   pre-eminence by 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-17th century 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 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. The waves
   resulted in more than 226,000 deaths and over 1 million were left
   homeless.

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, Maldives

   Port of Somalia, Somalia

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