What is the world's deepest known oceanic trench?

What is the world’s deepest known oceanic trench? The Mariana Trench is the world’s deepest known oceanic trench.

It lies in the western Pacific Ocean, east of the Mariana Islands, along a subduction zone where the Pacific Plate descends beneath the smaller Mariana Plate. The trench is crescent-shaped and stretches for roughly 2,550 kilometers. Its greatest depth is the Challenger Deep, a basin at the trench’s southern end.

Modern measurements place Challenger Deep at about 10,900 to 11,000 meters below sea level, though the exact figure varies with surveying methods and correction standards. That is deeper than Mount Everest is high, making the trench the most extreme known depression on Earth’s surface. The immense pressure at the bottom is more than 1,000 times standard atmospheric pressure.

The trench was first sounded during the HMS Challenger expedition of 1872–1876. The bathyscaphe Trieste reached the bottom in 1960, and filmmaker James Cameron made a solo descent in 2012. Later crewed and robotic missions have continued refining measurements.

The Tonga Trench is a frequent mix-up: it is also extraordinarily deep, but Challenger Deep remains deeper.