World Ocean - the single connected salty body of water that covers the majority of Earth's surface.
Ocean - the four to seven largest named bodies of water in the World Ocean, all of which have "Ocean" in the name. See Borders of the oceans for details.
Sea has several definitions:
A marginal sea - a marginal sea is a division of an ocean, partially enclosed by islands, archipelagos, or peninsulas, adjacent to or widely open to the open ocean at the surface, and/or bounded by submarine ridges on the sea floor.
A division of an ocean, delineated by landforms, currents (e.g. Sargasso Sea), or specific latitude or longitude boundaries. This includes but is not limited to marginal seas, and this is the definition used for inclusion in this list.
The World Ocean. For example, the Law of the Sea states that all of the World Ocean is 'sea', and this is also common usage for "the sea".
Any large body of water with "Sea" in the name, including lakes.
Strait - a narrow area of water connecting two wider areas of water
There are several terms used for bulges of ocean that result from indentations of land, which overlap in definition, and which are not consistently differentiated:
Bay - generic term; though most features with "Bay" in the name are small, some are very large
Gulf - a very large bay, often a top-level division of an ocean or sea
Fjord - a long bay with steep sides, typically formed by a glacier
Bight - a bay that is typically shallower than a sound
Sound - a large, wide bay which is typically deeper than a bight, or a strait
Cove - a very small, typically sheltered bay
Many features could be considered to be more than one of these, and all of these terms are used in place names inconsistently; especially bays, gulfs, and bights, which can be very large or very small. This list includes large areas of water no matter the term used in the name.
There is no accepted technical definition of sea among oceanographers. A rather weak definition is that a sea is a subdivision of an ocean, which means that it must have oceanic basin crust on its floor. This definition, for example, accepts the Caspian Sea, which was once part of an ancient ocean, as a sea. The Introduction to Marine Biology defines a sea as a 'landlocked' body of water, adding that the term "sea" is only one of convenience, but the book is written by marine biologists, not oceanographers. The Glossary of Mapping Sciences similarly states that the boundaries between seas and other bodies of water are arbitrary. According to this definition, the Caspian would be excluded as it is legally an 'international lake'.
|sq. mi.||sq. km||ft.||m||ft.||m|
|1. Pacific Ocean||64,000,000||165,760,000||13,215||4,028||36,198||11,033||Mariana Trench|
|2. Atlantic Ocean||31,815,000||82,400,000||12,880||3,926||30,246||9,219||Puerto Rico Trench|
|3. Indian Ocean||25,300,000||65,526,700||13,002||3,963||24,460||7,455||Sunda Trench|
|4. Arctic Ocean||5,440,200||14,090,000||3,953||1,205||18,456||5,625||77* 45'N. 175*W.|
|5. Mediterranean Sea1||1,145,100||2,965,800||4,688||1,429||15,197||4,632||Cape Matapan, Greece|
|6. Caribbean Sea||1,049,500||2,718,200||8,685||2,647||22,788||6,946||By Cayman Island|
|7. South China Sea||895,400||2,319,000||5,419||1,652||16,456||5,016||West of Luzon|
|8. Bering Sea||884,900||2,291,900||5,075||1,547||15,659||4,773||by Buldir Island|
|9. Gulf of Mexico||615,000||1,592,800||4,874||1,486||12,425||3,787||Sigsbee Deep|
|10. Okhotsk Sea||613,800||1,589,700||2,749||838||12,001||3,658||146*10'E. 46*50'N.|
|11. East China Sea||482,300||1,249,200||617||188||9,126||2,782||25*16'N. 125*E.|
|12. Hudson Bay||475,800||1,232,300||420||128||600||183||Near entrance|
|13. Japan Sea||389,100||1,007,800||4,429||1,350||12,276||3,742||Central Basin|
|14. Andaman Sea||308,100||797,700||2,854||870||12,392||3,777||By Car Nicobar Island|
|15. North Sea||222,100||575,200||308||94||2,165||660||Skagerrak|
|16. Red Sea||169,100||438,000||1,611||491||7,254||2,211||By Port Sudan|
|17. Baltic Sea||163,000||422,200||180||55||1,380||421||By Gotland|