Indian Ocean

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The INDIAN OCEAN is the third largest of the world's oceanic divisions, covering 70,560,000 km2 (27,240,000 sq mi) (approximately 20% of the water on the Earth
Earth 's surface). It is bounded by Asia
Asia on the north, on the west by Africa
Africa , on the east by Australia
Australia , and on the south by the Southern Ocean or, depending on definition, by Antarctica
Antarctica . It is named after the Indian subcontinent . The Indian Ocean
Ocean is known as _Ratnākara_ ( Sanskrit
Sanskrit : रत्नाकर), "_the mine of gems_" in ancient Sanskrit
Sanskrit literature, and as _Hind Mahāsāgar_ ( Hindi
Hindi : हिन्द महासागर), in Hindi .

CONTENTS

* 1 Geography

* 1.1 Marginal seas

* 2 Climate * 3 Oceanography * 4 Geology * 5 Marine life

* 6 History

* 6.1 First settlements * 6.2 Era of discovery * 6.3 Industrial era * 6.4 Contemporary era

* 7 Trade

* 7.1 Major ports and harbours

* 8 Bordering countries and territories * 9 See also

* 10 References

* 10.1 Notes * 10.2 Sources

* 11 External links

GEOGRAPHY

A - 17th century
17th century - 1658 Naval
Naval Map by Janssonius depicting the Indian Ocean
Ocean , India
India and Arabia
Arabia .

The borders of the Indian Ocean
Ocean , as delineated by the International Hydrographic Organization in 1953 included the Southern Ocean but not the marginal seas along the northern rim, but in 2000 the IHO delimited the Southern Ocean separately, which removed waters south of 60°S from the Indian Ocean, but included the northern marginal seas. Meridionally , the Indian Ocean
Ocean is delimited from the Atlantic Ocean by the 20° east meridian , running south from Cape Agulhas , and from the Pacific Ocean
Pacific Ocean by the meridian of 146°55'E, running south from the southernmost point of Tasmania
Tasmania . The northernmost extent of the Indian Ocean
Ocean is approximately 30° north in the Persian Gulf
Persian Gulf .

The Indian Ocean
Ocean covers 70,560,000 km2 (27,240,000 sq mi), including the Red Sea
Red Sea and the Persian Gulf
Persian Gulf but excluding the Southern Ocean, or 19.5% of the world's oceans; its volume is 264,000,000 km3 (63,000,000 cu mi) or 19.8% of the world's oceans' volume; it has an average depth of 3,741 m (12,274 ft) and a maximum depth of 7,906 m (25,938 ft).

The ocean's continental shelves are narrow, averaging 200 kilometres (120 mi) in width. An exception is found off Australia's western coast, where the shelf width exceeds 1,000 kilometres (620 mi). The average depth of the ocean is 3,890 m (12,762 ft). Its deepest point is Diamantina Deep in Diamantina Trench , at 8,047 m (26,401 ft) deep; Sunda Trench has a depth of 7,258–7,725 m (23,812–25,344 ft). 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.

The major choke points include Bab el Mandeb , Strait of Hormuz
Strait of Hormuz , the Lombok Strait , the Strait of Malacca and the Palk Strait . Seas include the Gulf of Aden
Gulf of Aden , Andaman Sea , Arabian Sea
Arabian Sea , Bay of Bengal
Bay of Bengal , Great Australian Bight , Laccadive Sea , Gulf of Mannar , Mozambique Channel , Gulf of Oman , Persian Gulf
Persian Gulf , Red Sea
Red Sea and other tributary water bodies. The Indian Ocean
Ocean is artificially connected to the Mediterranean Sea
Mediterranean Sea through the Suez Canal
Suez Canal , which is accessible via the Red Sea. All of the Indian Ocean
Ocean is in the Eastern Hemisphere and the centre of the Eastern Hemisphere is in this ocean.

MARGINAL SEAS

Marginal seas , gulfs, bays and straits of the Indian Ocean
Ocean include:

* Andaman Sea * Arabian Sea
Arabian Sea * Bay of Bengal
Bay of Bengal * Great Australian Bight * Gulf of Mannar * Gulf of Aden
Gulf of Aden * Gulf of Aqaba * Gulf of Tadjoura * Gulf of Bahrain * Gulf of Carpentaria * Gulf of Kutch * Gulf of Khambat * Gulf of Oman * Indonesian Seaway (including the Malacca , Sunda and Torres Straits ) * Laccadive Sea * Mozambique Channel * Palk Strait connecting Arabian Sea
Arabian Sea and Bay of Bengal * Persian Gulf
Persian Gulf * Red Sea
Red Sea * Sea of Zanj * Strait of Bab-el-Mandeb connecting Arabian Sea * Strait of Hormuz
Strait of Hormuz connecting Persian Gulf

CLIMATE

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

The Indian Ocean
Ocean is the warmest ocean in the world. Long-term ocean temperature records show a rapid, continuous warming in the Indian Ocean, at about 0.7–1.2 °C (1.3–2.2 °F) during 1901–2012. Indian Ocean
Ocean warming is the largest among the tropical oceans, and about 3 times faster than the warming observed in the Pacific. Research indicates that human induced greenhouse warming , and changes in the frequency and magnitude of El Niño events are a trigger to this strong warming in the Indian Ocean.

OCEANOGRAPHY

Among the few large rivers flowing into the Indian Ocean
Ocean are the Zambezi
Zambezi , Shatt al-Arab , Indus , Godavari
Godavari , Krishna , Narmada
Narmada , Ganges
Ganges , Brahmaputra , Jubba and Irrawaddy . The ocean's currents are mainly controlled by the monsoon. Two large gyres , one in the northern hemisphere flowing clockwise and one south of the equator moving anticlockwise (including the Agulhas Current and Agulhas Return Current ), constitute the dominant flow pattern. During the winter monsoon, however, currents in the north are reversed.

Deep water circulation is controlled primarily by inflows from the Atlantic Ocean
Atlantic Ocean , the Red Sea
Red Sea , and Antarctic
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.

Precipitation and evaporation leads to salinity variation in all oceans, and in the Indian Ocean
Ocean salinity variations are driven by: (1) river inflow mainly from the Bay of Bengal
Bay of Bengal , (2) fresher water from the Indonesian Throughflow
Indonesian Throughflow ; and (3) saltier water from the Red Sea and Persian Gulf
Persian Gulf . Surface water salinity ranges from 32 to 37 parts per 1000, the highest occurring in the Arabian Sea
Arabian Sea and in a belt between southern Africa
Africa and south-western 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 .

GEOLOGY

Bathymetric map of the Indian Ocean
Ocean Main category: Landforms of the Indian Ocean
Ocean

As the youngest of the major oceans, the Indian Ocean
Ocean has active spreading ridges that are part of the worldwide system of mid-ocean ridges . In the Indian Ocean
Ocean these spreading ridges meet at the Rodrigues Triple Point with the Central Indian Ridge , including the Carlsberg Ridge , separating the African Plate from the Indian Plate
Indian Plate ; the Southwest Indian Ridge separating the African Plate form the Antarctic Plate ; and the Southeast Indian Ridge
Southeast Indian Ridge separating the Australian Plate from the Antarctic Plate .The Central Ridge runs north on the in-between across of the Arabian Peninsula and Africa into the Mediterranean Sea
Mediterranean Sea .

A series of ridges and seamount chains produced by hotspots pass over the Indian Ocean. The Réunion hotspot (active 70–40 million years ago) connects Réunion
Réunion and the Mascarene Plateau
Mascarene Plateau to the Chagos-Laccadive Ridge and the Deccan Traps
Deccan Traps in north-western India; the Kerguelen hotspot
Kerguelen hotspot (100–35 million years ago) connects the Kerguelen Islands
Kerguelen Islands and Kerguelen Plateau to the Ninety East Ridge and the Rajmahal Traps in north-eastern India; the Marion hotspot (100–70 million years ago) possibly connects Prince Edward Islands to the Eighty Five East Ridge . It should be noted that these hotspot tracks have been broken by the still active spreading ridges mentioned above.

MARINE LIFE

Among the tropical oceans, the western Indian Ocean
Ocean hosts one of the largest concentration of phytoplankton blooms in summer, due to the strong monsoon winds. The monsoonal wind forcing leads to a strong coastal and open ocean upwelling , which introduces nutrients into the upper zones where sufficient light is available for photosynthesis and phytoplankton production. These phytoplankton blooms support the marine ecosystem, as the base of the marine food web, and eventually the larger fish species. The Indian Ocean
Ocean accounts for the second largest share of the most economically valuable tuna catch. Its fish are of great and growing importance to the bordering countries for domestic consumption and export. Fishing fleets from Russia
Russia , Japan
Japan , South Korea
South Korea , and Taiwan
Taiwan also exploit the Indian Ocean, mainly for shrimp and tuna.

Research indicates that increasing ocean temperatures are taking a toll on the marine ecosystem. A study on the phytoplankton changes in the Indian Ocean
Ocean indicates a decline of up to 20% in the marine phytoplankton in the Indian Ocean, during the past six decades. The tuna catch rates have also declined abruptly during the past half century, mostly due to increased industrial fisheries, with the ocean warming adding further stress to the fish species.

Endangered marine species include the dugong , seals , turtles , and whales .

An Indian Ocean
Ocean garbage patch was discovered in 2010 covering at least 5 million square kilometres (1.9 million square miles). Riding the southern Indian Ocean
Ocean Gyre , this vortex of plastic garbage constantly circulates the ocean from Australia
Australia to Africa, down the Mozambique Channel , and back to Australia
Australia in a period of six years, except for debris that get indefinitely stuck in the centre of the gyre.

In 2016, UK researchers from Southampton University identified six new animal species at hydrothermal vents beneath the Indian Ocean. These new species were a "Hoff" crab, a "giant peltospirid" snail, a whelk-like snail, a limpet, a scaleworm and a polychaete worm.

HISTORY

The economically important Silk Road (red) and spice trade routes (blue) were blocked by the Ottoman Empire
Ottoman Empire in c. 1453 with the fall of the Byzantine Empire
Byzantine Empire . This spurred exploration, and a new sea route around Africa
Africa was found, triggering the Age of Discovery .

FIRST SETTLEMENTS

The history of the Indian Ocean
Ocean is marked by maritime trade; cultural and commercial exchange probably date back at least seven thousand years. During this period, independent, short-distance oversea communications along its littoral margins have evolved into an all-embracing network. The début of this network was not the achievement of a centralised or advanced civilisation but of local and regional exchange in the Persian Gulf, the Red Sea, and Arabian Sea. Sherds of Ubaid (2500–500 BCE) pottery have been found in the western Gulf at Dilmun
Dilmun , present-day Bahrain
Bahrain ; traces of exchange between this trading centre and Mesopotamia
Mesopotamia . Sumerian traded grain, pottery, and bitumen (used for reed boats ) for copper, stone, timber, tin, dates, onions, and pearls. Coast-bound vessels transported goods between the Harappa civilisation (2600–1900 BCE
BCE ) in India (modern-day Pakistan
Pakistan and Gujarat in India) and the Persian Gulf
Persian Gulf and Egypt.

_ Periplus of the Erythraean Sea _, an Alexandrian guide to the world beyond the Red Sea
Red Sea — including Africa
Africa and India
India — from the first century CE, not only gives insights into trade in the region but also shows that Roman and Greek sailors had already gained knowledge about the monsoon winds. The contemporaneous settlement of Madagascar
Madagascar by Indonesian sailors shows that the littoral margins of the Indian Ocean were being both well-populated and regularly traversed at least by this time. Albeit the monsoon must have been common knowledge in the Indian Ocean
Ocean for centuries.

The world's earliest civilizations in Mesopotamia
Mesopotamia (beginning with Sumer
Sumer ), ancient Egypt
Egypt , and the Indian subcontinent (beginning with the Indus Valley civilization ), which began along the valleys of the Tigris
Tigris - Euphrates
Euphrates , Nile
Nile and Indus rivers respectively, all developed around the Indian Ocean. Civilizations soon arose in Persia (beginning with Elam
Elam ) and later in Southeast Asia
Southeast Asia (beginning with Funan ).

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

The Indian Ocean's relatively calmer waters opened the areas bordering it 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 ancient Indonesian peoples to cross the Indian Ocean
Ocean to settle in Madagascar
Madagascar around 1 CE.

ERA OF DISCOVERY

In the 2nd or 1st century BCE, Eudoxus of Cyzicus was the first Greek to cross the Indian Ocean. The probably fictitious sailor Hippalus is said to have discovered the direct route from Arabia
Arabia to India
India around this time. During the 1st and 2nd centuries AD intensive trade relations developed between Roman Egypt
Egypt and the Tamil kingdoms of the Cheras , Cholas and Pandyas in Southern India
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, as well as the commodities that were traded along various commercial ports on the coasts of the Horn of Africa
Africa and India
India circa 1 CE. Among these trading settlements were Mosylon
Mosylon and Opone on the Red Sea
Red Sea littoral.

Unlike the Pacific Ocean
Pacific Ocean where the civilization of the Polynesians reached most of the far flung islands and atolls and populated them, almost all the islands, archipelagos and atolls of the Indian Ocean were uninhabited until colonial times. Although there were numerous ancient civilizations in the coastal states of Asia
Asia and parts of Africa, the Maldives
Maldives were the only island group in the Central Indian Ocean
Ocean region where an ancient civilization flourished. Maldivian ships used the Indian Monsoon
Monsoon Current to travel to the nearby coasts.

From 1405 to 1433 Admiral Zheng He led large fleets of the Ming Dynasty on several treasure voyages through the Indian Ocean, ultimately reaching the coastal countries of East Africa
East Africa . _ British heavy cruisers Dorsetshire _ and _Cornwall _ under Japanese air attack and heavily damaged on 5 April 1942

In 1497 Portuguese navigator Vasco da Gama
Vasco da Gama rounded the Cape of Good Hope and became the first European to sail to India
India and later the Far East . The European ships, armed with heavy cannon, quickly dominated trade. Portugal
Portugal achieved pre-eminence by setting up forts at the important straits and ports. Their hegemony along the coasts of Africa and Asia
Asia lasted until the mid 17th century. Later, the Portuguese were challenged by other European powers. The Dutch East India
India Company (1602–1798) sought control of trade with the East across the Indian Ocean. France
France and Britain established trade companies for the area. From 1565 Spain
Spain established a major trading operation with the Manila Galleons in the Philippines
Philippines and the Pacific . Spanish trading ships purposely avoided the Indian Ocean, following the Treaty of Tordesillas with Portugal. By 1815, Britain became the principal power in the Indian Ocean.

INDUSTRIAL ERA

The opening of the Suez Canal
Suez Canal in 1869 revived European interest in the East, but no nation was successful in establishing trade dominance. Since World War II
World War II the United Kingdom was forced to withdraw from the area, to be replaced by India, the USSR , and the United States
United States . The last two 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. The United Kingdom and United States maintain a military base on Diego Garcia atoll in the middle of the Indian Ocean.

CONTEMPORARY ERA

On 26 December 2004 the countries surrounding the Indian Ocean
Ocean were hit by a tsunami caused by the 2004 Indian Ocean
Ocean earthquake . The waves resulted in more than 226,000 deaths and over 1 million people were left homeless.

In the late 2000s the ocean evolved into a hub of pirate activity. By 2013, attacks off the Horn region's coast had steadily declined due to active private security and international navy patrols, especially by the Indian Navy.

Malaysian Airlines flight MH370, a Boeing 777 airliner with 239 persons on board, disappeared on 8 March 2014 and is alleged to have crashed into the southeastern Indian Ocean
Ocean about 2,000km from the coast of southwest Western Australia
Australia . Despite an extensive search, the whereabouts of the remains of the aircraft are unknown.

TRADE

Main article: Indian Ocean
Ocean trade A dhow off the coast of Kenya
Kenya

The Indian Ocean
Ocean provides major sea routes connecting the Middle East , Africa
Africa , and East Asia
Asia with Europe
Europe and the Americas
Americas . It carries a particularly heavy traffic of petroleum and petroleum products from the oil fields of the Persian Gulf
Persian Gulf and Indonesia
Indonesia . Large reserves of hydrocarbons are being tapped in the offshore areas of Saudi Arabia
Arabia , Iran
Iran , India
India , and Western Australia
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
India , Pakistan
Pakistan , South Africa
Africa , Indonesia
Indonesia , Sri Lanka
Sri Lanka , and Thailand
Thailand .

MAJOR PORTS AND HARBOURS

Main article: List of ports and harbours of the Indian Ocean
Ocean

The Port of Singapore is the busiest port in the Indian Ocean, located in the Strait of Malacca where it meets the Pacific. Mumbai , Trivandrum
Trivandrum , Chennai , Kolkata , Kochi , Mormugao Port , Mundra
Mundra , Panambur , Hazira , Port Blair , Alang , Visakhapatnam
Visakhapatnam , Paradip , Ennore , Tuticorin and Nagapattinam are the other major ports in India. South Asian ports include Chittagong in Bangladesh
Bangladesh , Colombo
Colombo , Hambantota and Galle
Galle in Sri Lanka
Sri Lanka , and ports of Karachi
Karachi , Sindh province and Gwadar , Balochistan
Balochistan province in Pakistan. Aden
Aden is a major port in Yemen
Yemen and controls ships entering the Red Sea
Red Sea . Major African ports on the shores of the Indian Ocean
Ocean include: Mombasa (Kenya), Dar es Salaam , Zanzibar
Zanzibar ( Tanzania
Tanzania ), Durban
Durban , East London , Richard\'s Bay (South Africa
Africa ), Beira ( Mozambique
Mozambique ), and Port Louis ( Mauritius
Mauritius ). Zanzibar
Zanzibar is especially famous for its spice export. Other major ports in the Indian Ocean
Ocean include Muscat ( Oman
Oman ), Yangon ( Burma
Burma ), Jakarta
Jakarta , Medan ( Indonesia
Indonesia ), Fremantle
Fremantle (port servicing Perth
Perth , Australia
Australia ) and Dubai (UAE).

Chinese companies have made investments in several Indian Ocean ports, including Gwadar , Hambantota , Colombo
Colombo and Sonadia . This has sparked a debate about the strategic implications of these investments.

BORDERING COUNTRIES AND TERRITORIES

Small islands dot the continental rims. Island nations within the ocean are Madagascar
Madagascar (the world\'s fourth largest island ), Bahrain
Bahrain , Comoros , Maldives
Maldives , Mauritius
Mauritius , Seychelles
Seychelles and Sri Lanka
Sri Lanka . The archipelago of Indonesia
Indonesia and the island nation of East Timor
East Timor border the ocean on the east.

Heading roughly clockwise, the states and territories (in italics) with a coastline on the Indian Ocean
Ocean (including the Red Sea
Red Sea and Persian Gulf) are:

AFRICA

* _ South Africa
Africa * Mozambique
Mozambique * Madagascar
Madagascar * French Southern and Antarctic Lands _ (FRA) * France
France ( Mayotte and Réunion
Réunion ) * Mauritius
Mauritius * Comoros * Tanzania
Tanzania * Seychelles
Seychelles * Kenya
Kenya * Somalia
Somalia * Djibouti
Djibouti * Eritrea
Eritrea * Sudan
Sudan * Egypt
Egypt