The deepest part of the ocean was first pinpointed in 1951 by HM Survey Ship Challenger in the Mariana Trench in the Pacific Ocean. On 23 January 1960 the manned US Navy bathyscaphe Trieste descended to the bottom, and on 24 March 1995 the unmanned Japanese probe Kaiko recorded a depth of 10,911 m (35,797 ft), the most accurately ever measured, when it also reached the bottom. 

If Mount Everest was dropped into the Mariana Trench, it would disappear 2,000 metres below the surface.