Oceans and Seas

The Earth's many waters

In the absolute broadest terms, the earth's surface is mostly covered by a continuous body of saltwater known as the global ocean. But, do to variations in climate, weather, and wildlife, (and for the sake of being able to describe the locations of things) people have found it useful to divide the ocean into many constituent parts.

The following table lists the world's oceans and seas, according to area and average depth, including the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern Ocean, Mediterranean Sea, Arctic Ocean, Caribbean Sea, Bering Sea, and more.

Greatest known
Place of
greatest known depth
sq. mi.sq. kmft.mft.m
Pacific Ocean60,060,700155,557,00013,2154,02836,19811,033Mariana Trench
Atlantic Ocean29,637,90076,762,00012,8803,92630,2469,219Puerto Rico Trench
Indian Ocean26,469,50068,556,00013,0023,96324,4607,455Sunda Trench
Southern Ocean17,848,30020,327,00013,100?16,4004,000?5,00023,7367,235South Sandwich Trench
Arctic Ocean5,427,00014,056,0003,9531,20518,4565,6257745'N; 175W
Mediterranean Sea21,144,8002,965,8004,6881,42915,1974,632Off Cape Matapan, Greece
Caribbean Sea1,049,5002,718,2008,6852,64722,7886,946Off Cayman Islands
South China Sea895,4002,319,0005,4191,65216,4565,016West of Luzon
Bering Sea884,9002,291,9005,0751,54715,6594,773Off Buldir Island
Gulf of Mexico615,0001,592,8004,8741,48612,4253,787Sigsbee Deep
Okhotsk Sea613,8001,589,7002,74983812,0013,65814610'E; 4650'N
East China Sea482,3001,249,2006171889,1262,7822516'N; 125E
Hudson Bay475,8001,232,300420128600183Near entrance
Japan Sea389,1001,007,8004,4291,35012,2763,742Central Basin
Andaman Sea308,000797,7002,85487012,3923,777Off Car Nicobar Island
North Sea222,100575,200308942,165660Skagerrak
Red Sea169,100438,0001,6114917,2542,211Off Port Sudan
Baltic Sea163,000422,200180551,380421Off Gotland
NOTE: For Caspian Sea, see Large Lakes of the World.
1. A decision by the International Hydrographic Organization in spring 2000 delimited a fifth world ocean.
2. Includes Black Sea and Sea of Azov.

The Seven Seas

Most people will be aware of the phrase "the seven seas", which is common in pop culture about sailors and seadogs. The term itself is very old, with variations being found in Ancient Mesopotamia, India, and Rome. The seven seas in each case refer to different bodies of water. In Rome, the seven seas aren't even seas at all but lagoons. In medieval Arabia, it referred to the seas between Arabia and China. It effectively just means "all of the seas that are particularly important to us".

In the modern era, the phrase has been applied to a group of seven oceans: the Arctic Ocean, the North Atlantic Ocean, the South Atlantic Ocean, the Indian Ocean, the North Pacific Ocean, the South Pacific Ocean, and the Antarctic Ocean.

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