what are ocean trenches
Ocean trenches have relatively steep sides falling to the ocean floor. Ocean trenches are typically caused when an oceanic crustal plate slides under a lighter continental plate or another oceanic plate. It is believed to work by density.Where one plate slides under another, this is called subduction.t least five trenches are over 6 miles (10 km) deep. The greatest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench, at a depth of 11,034 m (36,201 ft) below sea level.