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Mariana Trench

The Mariana Trench is the deepest known oceanic trench on Earth and the deepest known part of the planet’s crust.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

The Mariana Trench is the deepest known oceanic trench on Earth and the deepest known part of the planet’s crust. It lies in the western Pacific Ocean, east of the Mariana Islands and near Guam. The trench includes Challenger Deep, its lowest known point.

Geography

The Mariana Trench is a long, narrow crescent-shaped trench in the western Pacific Ocean. It extends for about 2,550 km and is roughly 70 km wide.

Geology

The trench is a subduction zone formed by the Pacific Plate descending beneath the Philippine Sea Plate. This tectonic setting is responsible for its extreme depth.

Challenger Deep

Challenger Deep is the lowest known point in the trench and one of the deepest measured points on Earth. Recent measurements place it at about 10,984 metres below sea level, though published figures vary by survey.

Exploration

The trench has been surveyed by multiple expeditions, including historic deep-sea exploration and modern sonar and submersible missions. It remains an important site for studying deep-ocean geology and biology.

Key facts

  • It is the deepest known oceanic trench on Earth.
  • The trench arcs roughly north–south in a crescent shape.
  • Challenger Deep is the trench’s deepest known point.
  • The trench is located east of the Mariana Islands in the western Pacific.
  • It formed at a convergent plate boundary where the Pacific Plate subducts beneath the Philippine Sea Plate.
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Canadian context

Canadian scientists and oceanographic institutions have participated in deep-ocean research, and the Mariana Trench is a reference point in studies of Earth’s deepest marine environments.

Frequently asked questions

What is the Mariana Trench?
It is the deepest known oceanic trench on Earth, located in the western Pacific Ocean.
Where is it located?
It lies east of the Mariana Islands, near Guam, in the western Pacific.
What is the deepest point called?
The deepest point is called Challenger Deep.
How deep is it?
The deepest measured depth commonly cited is 10,984 ± 25 metres.
How long is the trench?
It is about 2,550 kilometres long.
How did it form?
It formed at a subduction zone where the Pacific Plate moves beneath the Philippine Sea Plate.

References

  1. Wikipedia — https://fr.wikipedia.org/wiki/Fosse_des_Mariannes
    Supports: Location, dimensions, Challenger Deep depth, and general description.
  2. Nausicaá — https://www.nausicaa.fr/fr/le-mag-ocean/fosse-des-mariannes-11-000-metres-sous-les-mers
    Supports: Pacific location and tectonic subduction context.
  3. GEO — https://www.geo.fr/environnement/ou-se-situe-la-fosse-des-mariannes-la-fosse-la-plus-profonde-du-monde-227570
    Supports: Location, length, width, Challenger Deep depth, and nearest islands.
  4. Techno-Science — https://www.techno-science.net/definition/1109.html
    Supports: Deepest-known trench description and plate-boundary setting.