Oceanic trench the level of the surrounding oceanic floor. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of below sea level. Oceanic lithosphere moves into trenches at a global rate of about 3 km/yr. There are approximately of convergent plate margins, mostly around the Pacific Ocean—the reason for the reference “Pacific-type” margin—but they are also in the eastern Indian Ocean, with relatively short convergent margin segments in the Atlantic Ocean and in the Mediterranean Sea. Globally, there are over 50 major ocean trenches covering an area of 1.9 million km or about 0.5%
Mariana Trench Mariana Trench The Mariana Trench or Marianas Trench is located in the western Pacific Ocean approximately east of the Mariana Islands, and has the deepest natural point in the world. It is a crescent-shaped trough in the Earth's crust averaging about long and wide. The maximum known depth is (± ) 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 . For comparison: if Mount Everest were dropped into the trench at this point, its peak would still be over under water. At