Global characteristics
Total surface of the earth: 510 million square kilometres.
Area covered by land: 149 million square kilometres (29%).
Area covered by water: 361 million square kilometres (71%).
93% of the water coverage is made up of 5 oceans:
- Pacific Ocean 155.6 million square kilometres.
- Atlantic Ocean 76.8 million square kilometres.
- Indian Ocean 68.6 million square kilometres.
- Southern Ocean 20.3 million square kilometres.
- Arctic Ocean 14.1 million square kilometres.
The other 7% of the water coverage (about 26 million square kilometres) is made up of adjacent seas:
Of these, the largest section is taken up by three Mediterranean seas (European Mediterranean; Caribbean Mediterranean (incl. Gulf of Mexico); and the East Indian Archipelago]: about 15 million square kilometres.
The small mediterranean seas represent 2.3 million square kilometres (Red Sea, Persian Gulf, Baltic, Hudson Bay).
The marginal seas make up about 8 million square kilometres [e.g. North Sea, English Channel, Irish Sea, Japan Sea, Gulf of California, etc].
Ocean boundaries
The official maritime boundaries are decided by the International Hydrographic Organisation:
The maritime boundaries of the 5 Oceans are
(see http://en.wikipedia.org/wiki/File:World_ocean_map.gif):
- Atlantic-Indian: Cape Agulhas, South Africa.
- Indian Pacific: Islands in Indonesia, and south of Tasmania (Australia).
- Pacific-Atlantic: South of Cape Horn, South America.
- Northern boundary of the Southern Ocean: 60 degrees S.
- Southern boundary of the Arctic Ocean: Varies, but located north of Greenland, Canada, Alaska, Russia, Norway. (http://en.wikipedia.org/wiki/Arctic_Ocean#Extent.
Global means and extremes
- Deepest point: The Marianas Trench in the western Pacific: depth 10 924m.
- Average depth of the global ocean: 3 800m.
- Most common depth: 4420m (this corresponds to the abyssal plains).
- Averageland elevation: 840m.
- Most common land elevation: 270m (this corresponds to the height of the continental plateau).
Topography of the bottom
From: Gross, Oceanography: a view of the earth, 1977