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.

Geographic coordinates: 20 00 S, 80 00 E

Map reference: Political Map of the World

Area
Note: includes Andaman Sea, Arabian Sea, Bay of Bengal, Flores Sea, Great Australian Bight, Gulf of Aden, Gulf of Oman, Java Sea, Mozambique Channel, Persian Gulf, Red Sea, Savu Sea, Strait of Malacca, Timor Sea, and other tributary water bodies
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

Elevation
Mean depth: -3,741 m
Lowest point: Java Trench -7,258 m
Highest point: sea level

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

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

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

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

Disputes international: some maritime disputes (see littoral states)