The Marianas Trench, about 210 miles (338 km)south of Guam, is the location of the deepest place in any ocean (36,198 ft/11,033 m). Its distance to sea level is a good 7163 ft (2183 m) more than Mount Everest.

The location was found in 1951 by a British survey vessel, the Challenger II and therefore named Challenger Deep. In 1960, the US Navy sent a small submersible, the Trieste to the bottom of Challenger Deep, manned by Lieutenant Don Walsh and Jacques Piccard. This achievement has never been repeated.