What is the deepest known point in Earth’s oceans, inside the Mariana Trench?

Challenger Deep is the deepest known point in Earth’s oceans, lying inside the Mariana Trench in the western Pacific Ocean.

Modern measurements place its deepest surveyed floor at roughly 10,900 metres below sea level, although exact figures vary with instruments, location, and correction methods. The depression lies where the Pacific Plate is forced beneath the Philippine Sea Plate, a process called subduction.

The name comes from HMS Challenger, whose expedition made early deep-sea measurements in the region during the 19th century. In 1960, Jacques Piccard and Don Walsh reached the bottom in the bathyscaphe Trieste. Later crewed and uncrewed expeditions have refined observations of the trench.

Challenger Deep is not a mountain-like hole with a single perfectly defined point; it consists of several basins within the trench. The Mariana Trench extends for more than 2,500 kilometres, and its extreme pressure makes exploration technically difficult.