The deepest part of Earth's oceans, where the Pacific Plate is subducted under the Mariana Plate
This article is about the deep sea trench. For the Canadian band named after the geological formation, see Marianas Trench (band).
Location of the Mariana Trench
The Mariana Trench or Marianas Trench is located in the western Pacific Ocean approximately 200 kilometres (124 mi) east of the Mariana Islands, and has the deepest natural trench in the world. It is a crescent-shaped trough in the Earth's crust averaging about 2,550 km (1,580 mi) long and 69 km (43 mi) wide. The maximum known depth is 10,994 metres (36,070 ft) (± 40 metres [130 ft]) at the southern end of a small slot-shaped valley in its floor known as the Challenger Deep. However, some unrepeated measurements place the deepest portion at 11,034 metres (36,201 ft). For comparison: if Mount Everest were dropped into the trench at this point, its peak would still be over two kilometres (1.2 mi) under water.[a]
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 95.27 litres (20.96 imp gal; 25.17 US gal) of water under the pressure of the Challenger Deep would contain the same mass as 100 litres (22 imp gal; 26 US gal) at the surface. The temperature at the bottom is 1 to 4 °C (34 to 39 °F).
The trench is not the part of the seafloor closest to the centre of the Earth. This is because the Earth is not a perfect sphere; its radius is about 25 kilometres (16 mi) smaller at the poles than at the equator. As a result, parts of the Arctic Ocean seabed are at least 13 kilometres (8.1 mi) closer to the Earth's centre than the Challenger Deep seafloor.
In 2009, the Marianas Trench was established as a United States National Monument.
The Mariana Trench is named for the nearby Mariana Islands (in turn named Las Marianas in honor of Spanish Queen Mariana of Austria, widow of Philip IV of Spain). The islands are part of the island arc that is formed on an over-riding plate, called the Mariana Plate (also named for the islands), on the western side of the trench.