What is underwater?

Underwater

Underwater 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 are covered by water. A majority of the planet's solid surface is abyssal plain, at depths between 4,000 and 5,500 metres (13,000 and 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.

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Some articles on underwater:

Combat Diving - Types of Frogman Operations
... troop landing, or other forms of unauthorized underwater surveying in denied waters ... Clandestine underwater work, e.g ... Recovering underwater objects ...
Scuba Diving Quarry - Popular Features of Dive Sites
... There are a wide range of underwater features which may contribute to the popularity of a dive site Accessibility is important, but not critical ... The Topography of the site Coral reefs, walls (underwater cliffs), rocky reefs, gullies, caves and swim-throughs (short tunnels or arches) can be spectacular ... Underwater visibility This can vary widely between sites and with time and other conditions ...
Skomer Marine Nature Reserve
... Skomer Marine Nature Reserve is an underwater marine nature reserve located off the coast of Pembrokeshire in Wales ... Common eelgrass, Zostera marina, one of the very few plants that flower underwater, grows on beds of sand and gravel in sheltered waters and its long, grass-like leaves form underwater lawns that ...
Submarine Navigation
... Submarine navigation underwater requires special skills and technologies not needed by surface ships ... The challenges of underwater navigation have become more important as submarines spend more time underwater, travelling greater distances and at higher speed ... Military submarines travel underwater in an environment of total darkness with neither windows nor lights ...
Underwater
... Underwater 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 ... Although a number of human activities are conducted underwater—such as research, scuba diving for work or recreation, or even underwater warfare with submarines, this very ... Even at a depth of 8 ft (2.4 m) underwater, an inability to equalize air pressure in the middle ear with outside water pressure can cause pain, and the tympanic membrane can rupture at depths ...

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