What is the deepest oceanic trench on Earth?

The deepest oceanic trench on Earth is the Mariana Trench. Its deepest point, Challenger Deep, reaches roughly 10,900 metres below sea level in the western Pacific Ocean.

The trench lies about 200 kilometres east of the Mariana Islands, near the boundary where the Pacific Plate is forced beneath the smaller Mariana Plate. This process, called subduction, creates the steep, crescent-shaped depression and also helps produce the volcanic island arc nearby.

The name Challenger Deep comes from HMS Challenger, whose 1870s expedition first identified the area’s exceptional depth. In 1960, Jacques Piccard and Don Walsh became the first people to reach the bottom in the bathyscaphe Trieste; filmmaker James Cameron made a solo descent in 2012.

A common mix-up is confusing the trench with Challenger Deep. The Mariana Trench is the larger geological feature; Challenger Deep is its deepest basin. The Tonga Trench is also extremely deep, but it does not surpass the Mariana’s measured depths.