The Pacific Ocean is the largest and deepest of the world ocean basins. Covering approximately 59 million square miles and containing more than half of the free water on Earth, the Pacific is by far the largest of the world's ocean basins. All of the world's continents could fit into the Pacific basin.

 

The Mariana Trench or Marianas Trench is the deepest part of the world's oceans.It is located in the western Pacific Ocean, an average of 200 kilometres (124 mi) to the east of the Mariana Islands, in the Western Pacific East of Philippines. It is a crescent-shaped scar in the Earth's crust, and measures about 2,550 km (1,580 mi) long and 69 km (43 mi) wide on average. It reaches a maximum-known depth of 10,994 metres (36,070 ft) (± 40 metres [130 ft]) at a small slot-shaped valley in its floor known as the Challenger Deep, at its southern end,although some unrepeated measurements place the deepest portion at 11,034 metres (36,201 ft).If Mount Everest were dropped into the trench at this point, its peak would still be over 1.6 kilometres (1 mi) underwater.In 2009, Marianas Trench was established as a United States National Monument.

 

At the bottom of the trench the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,000 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%, so that 95 litres of water under the pressure of the Challenger Deep would contain the same mass as 100 litres at the surface. The temperature at the top is 1 to 40C (34 to 390 F).