

Topic: Photos of Indian Ocean

Topic: Introduction
Background: The Indian Ocean is the third largest of the world's five oceans (after the Pacific Ocean and Atlantic Ocean, but larger than the Southern Ocean and Arctic Ocean). Four critically important access waterways are the Suez Canal (Egypt), Bab el Mandeb (Djibouti-Yemen), Strait of Hormuz (Iran-Oman), and Strait of Malacca (Indonesia-Malaysia).The decision by the International Hydrographic Organization in the spring of 2000 to delimit a fifth ocean, the Southern Ocean, removed the portion of the Indian Ocean south of 60 degrees south latitude.Visit the Definitions and Notes page to view a description of each topic.

Topic: Geography
Location: body of water between Africa, the Southern Ocean, Asia, and Australia
Geographic coordinates: 20 00 S, 80 00 E
Map references: Political Map of the World
Area: total: 70.560 million sq km

note: includes Andaman Sea, Arabian Sea, Bay of Bengal, Great Australian Bight, Gulf of Aden, Gulf of Oman, Mozambique Channel, Persian Gulf, Red Sea, Savu Sea, Strait of Malacca, Timor Sea, and other tributary water bodies
Area - comparative: almost 7 times the size of the US
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 a major gyre (broad, circular system of currents) in the southern Indian Ocean and a unique reversal of surface currents in the northern Indian Ocean; 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 major surface currents: the counterclockwise Indian Ocean Gyre comprised of the southward flowing warm Agulhas and East Madagascar Currents in the west, the eastward flowing South Indian Current in the south, the northward flowing cold West Australian Current in the east, and the westward flowing South Equatorial Current in the north; a distinctive annual reversal of surface currents occurs 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 clockwise currents, while high pressure over northern Asia from cold, falling, winter air results in the northeast monsoon and northeast-to-southwest winds and counterclockwise currentssurface dominated by a major gyre (broad, circular system of currents) in the southern Indian Ocean and a unique reversal of surface currents in the northern Indian Ocean; ocean floor is dominated by the Mid-Indian Ocean Ridge and subdivided by the Southeast Indian Ocean Ridge, Southwest Indian Ocean Ridge, and Ninetyeast Ridgemajor surface currents: the counterclockwise Indian Ocean Gyre comprised of the southward flowing warm Agulhas and East Madagascar Currents in the west, the eastward flowing South Indian Current in the south, the northward flowing cold West Australian Current in the east, and the westward flowing South Equatorial Current in the north; a distinctive annual reversal of surface currents occurs 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 clockwise currents, while high pressure over northern Asia from cold, falling, winter air results in the northeast monsoon and northeast-to-southwest winds and counterclockwise currents
Elevation: highest point: sea level

lowest point: Java Trench -7,192 m unnamed deep

mean depth: -3,741 m

ocean zones: Composed of water and in a fluid state, the oceans are delimited differently than the solid continents. Oceans are divided into three zones based on depth and light level. Although some sea creatures depend on light to live, others can do without it. Sunlight entering the water may travel about 1,000 m into the oceans under the right conditions, but there is rarely any significant light beyond 200 m.

The upper 200 m (656 ft) of oceans is called the euphotic, or "sunlight," zone. This zone contains the vast majority of commercial fisheries and is home to many protected marine mammals and sea turtles. Only a small amount of light penetrates beyond this depth. 

The zone between 200 m (656 ft) and 1,000 m (3,280 ft) is usually referred to as the "twilight" zone, but is officially the dysphotic zone. In this zone, the intensity of light rapidly dissipates as depth increases. Such a minuscule amount of light penetrates beyond a depth of 200 m that photosynthesis is no longer possible.

The aphotic, or "midnight," zone exists in depths below 1,000 m (3,280 ft). Sunlight does not penetrate to these depths and the zone is bathed in darkness.
Natural resources: oil and gas fields, fish, shrimp, sand and gravel aggregates, placer deposits, polymetallic nodules
Natural hazards: occasional icebergs pose navigational hazard in southern reaches
Geography - note: major chokepoints include Bab el Mandeb, Strait of Hormuz, Strait of Malacca, southern access to the Suez Canal, and the Lombok Strait
Map description: Indian Ocean map highlights the Ocean in relation to surrounding continents and shows the major chokepoints.Indian Ocean map highlights the Ocean in relation to surrounding continents and shows the major chokepoints.
Volume: Ocean volume: 264 million cu km

Percent of total ocean volume: 19.8%

Topic: Environment
Environment - current issues: marine pollution caused by ocean dumping, waste disposal, and oil spills; deep sea mining; oil pollution in Arabian Sea, Persian Gulf, and Red Sea; coral reefs threatened due climate change, direct human pressures, and inadequate governance, awareness, and political will; loss of biodiversity; endangered marine species include the dugong, seals, turtles, and whales
Marine fisheries: the Indian Ocean fisheries are the third most important in the world accounting for 15.3%, or 12,248,064 mt of the global catch in 2019; tuna, small pelagic fish, and shrimp are important species in these regions; the Food and Agriculture Organization delineated two fishing regions in the Indian Ocean: Eastern Indian Ocean region (Region 57) is the most important region and the fifth largest producing region in the world with 8.5%, or 6,784,778 mt, of the global catch in 2019; the region encompasses the waters north of 55º South latitude and east of 80º East longitude including the Bay of Bengal and Andaman Sea with the major producers including India (2,362,481 mt), Indonesia (1,940,558 mt), Burma (1,114,777 mt), Bangladesh (877,837 mt), and Sri Lanka (373,369 mt); the principal catches include shad, Skipjack tuna, mackerel, shrimp, and sardinellas Western Indian Ocean region (Region 51) is the world’s sixth largest producing region with more than 6.8% or 5,463,286 mt of the global catch in 2019; this region encompasses the waters north of 40º South latitude and west of 80º East longitude including the western Indian Ocean, Arabian Sea, Persian Gulf, and Red Sea as well as the waters along the east coast of Africa and Madagascar, the south coast of the Arabian Peninsula, and the west coast of India with major producers including India (2,207,125 mt), Oman (580,048 mt), Pakistan (341,730 mt), and Mozambique (274,791 mt); the principal catches include Skipjack and Yellowfin tuna, mackerel, sardines, shrimp, and cephalopods

Regional fisheries bodies: Indian Ocean Tuna Commission, Commission for the Conservation of Southern Bluefin Tuna, Regional Commission for Fisheries (Persian Gulf/Gulf of Oman), Southeast Asia Fisheries Development Center, Southwest Indian Ocean Fisheries Commission, South Indian Ocean Fisheries Agreementthe Indian Ocean fisheries are the third most important in the world accounting for 15.3%, or 12,248,064 mt of the global catch in 2019; tuna, small pelagic fish, and shrimp are important species in these regions; the Food and Agriculture Organization delineated two fishing regions in the Indian Ocean:Eastern Indian Ocean region (Region 57) is the most important region and the fifth largest producing region in the world with 8.5%, or 6,784,778 mt, of the global catch in 2019; the region encompasses the waters north of 55º South latitude and east of 80º East longitude including the Bay of Bengal and Andaman Sea with the major producers including India (2,362,481 mt), Indonesia (1,940,558 mt), Burma (1,114,777 mt), Bangladesh (877,837 mt), and Sri Lanka (373,369 mt); the principal catches include shad, Skipjack tuna, mackerel, shrimp, and sardinellas
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

Topic: Government
Country name: etymology: named for the country of India, which makes up much of its northern border

Topic: Economy
Economic 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 oilfields 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, South 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.

Topic: Transportation
Ports and terminals: major seaport(s): Chennai (Madras, India); Colombo (Sri Lanka); Durban (South Africa); Jakarta (Indonesia); Kolkata (Calcutta, India); Melbourne (Australia); Mumbai (Bombay, India); Richards Bay (South Africa)

Topic: Military and Security
Maritime threats: the International Maritime Bureau continues to report the territorial waters of littoral states and offshore waters as high risk for piracy and armed robbery against ships, particularly in the Gulf of Aden, along the east coast of Africa, the Bay of Bengal, and the Strait of Malacca; the presence of several naval task forces in the Gulf of Aden and additional anti-piracy measures on the part of ship operators, including the use of on-board armed security teams, have reduced incidents of piracy; 2021 saw one incident in the region of the Horn of Africa; the EU naval mission, Operation ATALANTA, continues its operations in the Gulf of Aden and Indian Ocean through 2022; naval units from Japan, India, and China also operate in conjunction with EU forces; China has established a logistical base in Djibouti to support its deployed naval units in the Horn of Africa 

the Maritime Administration of the US Department of Transportation has issued a Maritime Advisory (2022-003 Persian Gulf, Strait of Hormuz, Gulf of Oman, Arabian Sea, Red Sea-Threats to US and International Shipping from Iran) effective 28 February 2022, which states in part that "heightened military activities and increased political tensions in this region continue to present risk to commercial shipping...there is a continued possibility that Iran and/or its regional proxies could take actions against US and partner interests in the region;" Coalition Task Force (CTF) Sentinel has been established to provide escorts for commercial shipping transiting the Persian Gulf, Strait of Hormuz, and Gulf of Oman

Topic: Transnational Issues
Disputes - international: some maritime disputes (see littoral states)some maritime disputes (see littoral states)