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Mariana Trench

Mariana Trench location

This article is about the geographical feature. For the Canadian pop-punk band, see Marianas Trench (band).

The Mariana Trench (or Marianas Trench) is the deepest known submarine trench, with a maximum depth of about 11 km (6.8 miles), and the deepest location on the surface of the Earth's crust.

It is located in the floor of the western North Pacific Ocean, to the east and south of the Mariana Islands at 11°21′N, 142°12′E, near Guam.

The trench is the boundary where two tectonic plates meet, where the Pacific Plate is being subducted under the Philippine Plate. The bottom of the trench is farther below sea level than Mount Everest is above it. At the bottom, water exerts a pressure of 108.6 MPa, over one thousand times the standard atmospheric pressure at sea level.

Exploration
The trench was first surveyed in 1951 by the Royal Navy vessel Challenger, which gave its name to the deepest part of the trench, the Challenger Deep. Using echo sounding, the Challenger II measured a depth of 5 960 fathoms (10 900 metres, 35 760 ft) at 11°19′N, 142°15′E

In 1957, the Soviet vessel Vityaz reported a depth of 11 034 meters (36 200 ft), dubbed the Mariana Hollow.  

January 23, 1960: Trieste just before the dive:

In an unprecedented dive, the United States Navy bathyscaphe Trieste reached the bottom at 1:06 p.m. on January 23, 1960, with U.S. Navy Lieutenant Don Walsh and Jacques Piccard on board. Iron shot was used for ballast, with gasoline for buoyancy. The onboard systems indicated a depth of 11 521 meters (37 799 ft), but this was later revised to 10 916 meters (35 813 ft). At the bottom, Walsh and Piccard were surprised to discover soles or flounder about 30 cm (1 ft) long, as well as shrimp. According to Piccard, "The bottom appeared light and clear, a waste of firm diatomaceous ooze".

In 1962, the M.V. Spencer F. Baird recorded a greatest depth of 10 915 meters (35 810 ft). In 1984, the Japanese sent the Takuyō, a highly specialized survey vessel, to the Mariana Trench and collected data using a narrow, multi-beam echo sounder; they reported a maximum depth of 10 924 metres, also reported as 10 920 meters ± 10 meters). The most accurate measurement on record was taken by a Japanese probe, Kaikō, which descended unmanned to the bottom of the trench on March 24, 1995 and recorded a depth of 10 911 meters (35 798 ft).

The Woods Hole Oceanographic Institution is planning to send its Nereus hybrid remotely operated vehicle (HROV) to explore the trench in 2007 or 2008.