Mariana Trench Mariana Trench or Marianas Trench[1] is located in the western Pacific Ocean about 200 kilometres (124 mi) east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about 2,550 km (1,580 mi) in length and 69 km (43 mi) in width. The maximum known depth is 10,984 metres (36,037 ft) (± 25 metres [82 ft]) (6.825 miles) at the southern end of a small slot-shaped valley in its floor known as the Challenger Deep.[2] However, some unrepeated measurements place the deepest portion at 11,034 metres (36,201 ft).[3] If Mount Everest were hypothetically placed into the trench at this point, its peak would still be underwater by more than two kilometres (1.2 mi).[a]

At the bottom of the trench, the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,071 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%. The temperature at the bottom is 1 to 4 °C (34 to 39 °F).[6]

In 2009, the Marianas Trench was established as a US National Monument.[7] Monothalamea have been found in the trench by Scripps Institution of Oceanography researchers at a record depth of 10.6 kilometres (6.6 mi) below the sea surface.[8] Data has also suggested that microbial life forms thrive within the trench.