Underwater, sometimes shortened as U/W, is a term describing the realm below the surface of water where the water exists in a natural feature (called a body of water) such as an ocean, sea, lake, pond, or river. Three quarters of the planet earth is covered by water. A majority of the planet's solid surface is abyssal plain, at depths between 4000 and 5500 m (13,000 to 18,000 ft) below the surface of the oceans. The solid surface location on the planet closest to the center of the orb is the Challenger Deep, located in the Mariana Trench at a depth of 10,924 m (35,838 ft) under the sea.

Although a number of human activities are conducted underwater—such as scuba diving for work or recreation, or even underwater warfare with submarines—this very extensive environment on planet earth is hostile to humans in many ways and therefore little explored.

An immediate obstacle to human activity under water is the fact that human lungs cannot naturally function in this environment. Unlike the gills of fish, human lungs are adapted to the exchange of gases at atmospheric pressure, not liquids. Aside from simply having insufficient musculature to rapidly move water in and out of the lungs, a more significant problem for all air breathing animals, such as mammals and birds, is that water contains so little dissolved oxygen compared with atmospheric air. Air is around 21% O₂; water typically is less than 0.001% dissolved oxygen.

More on [ Underwater ]

Underwater - Twitter Search

Please check out You and I Underwater @ www.myspace.com/youandiunderwater THANK YOU! You won't be disappointed <3
Shenise_V (Shenise Villanueva) Thu, 17 Dec 2009 09:45:08 -0000
Please check out You and I Underwater @ www.myspace.com/youandiunderwater THANK YOU! You won't be disappointed <3
Master Guide for Underwater Digital Photography (Paperback ... http://bit.ly/5OAKOD
photowedding (Rob Hughes) Thu, 17 Dec 2009 09:44:17 -0000
Master Guide for Underwater Digital Photography (Paperback ... http://bit.ly/5OAKOD
Underwater tables & gravestones: did meso-neolithic people from Orkney cope with climate change? http://bit.ly/7Vzef9 Can we learn lessons?
helenscales (Helen Scales) Thu, 17 Dec 2009 09:40:53 -0000
Underwater tables & gravestones: did meso-neolithic people from Orkney cope with climate change? http://bit.ly/7Vzef9 Can we learn lessons?
Ancient Underwater Cities, Graham Hancock On C2C 02-07-02: http://pressword.blogspot.com/2009/12/ancient-underwater-cities-evidence-by.html
Graham__Hancock (Graham Hancock) Thu, 17 Dec 2009 09:38:11 -0000
Ancient Underwater Cities, Graham Hancock On C2C 02-07-02: http://pressword.blogspot.com/2009/12/ancient-underwater-cities-evidence-by.html
Corals create a landscape unlike anything on land, but this underwater world is threatened by climate change: http://ow.ly/MXjb #cop15
Arkive (ARKive) Thu, 17 Dec 2009 09:33:22 -0000
Corals create a landscape unlike anything on land, but this underwater world is threatened by climate change: http://ow.ly/MXjb #cop15
Amazon Holiday Toy List "Melissa & Doug Underwater 48-Piece Floor Puzzle" http://bit.ly/921i92
note_zaa (Atinat Sinprasongsak) Thu, 17 Dec 2009 09:31:12 -0000
Amazon Holiday Toy List "Melissa & Doug Underwater 48-Piece Floor Puzzle" http://bit.ly/921i92

Subscribe to Underwater RSS feed