Which ocean does the Mariana Trench lie in?

The Mariana Trench lies in the Pacific Ocean.

It is a crescent-shaped submarine depression in the western Pacific, east of the Mariana Islands. The trench formed at a subduction zone where the Pacific Plate is forced beneath the smaller Mariana Plate. This geological process also contributes to the region’s volcanic activity and earthquakes.

The trench’s deepest known area is Challenger Deep, which reaches roughly 10,900 metres below sea level, although exact measurements vary slightly by survey and equipment. The first crewed descent to Challenger Deep took place in 1960, when Jacques Piccard and Don Walsh reached the bottom in the bathyscaphe Trieste. Film director James Cameron made a solo descent in 2012. Challenger Deep is deeper than Mount Everest is tall, but the trench is not the longest feature on Earth’s seafloor.