How Deep Is the Ocean?

The deepest known point on Earth is at the bottom of the Mariana Trench, a depression in the floor of the western Pacific Ocean, just east of the Mariana Islands.

The Mariana Trench is 1,554 miles long and averages 44 miles wide. Within it, about 210 miles southwest of Guam, lies the deepest known point on Earth. Named the “Challenger Deep” for the British survey ship Challenger II that located it in 1951, this underwater gorge plunges to a depth of nearly 7 miles! It is deeper than Mt. Everest is tall.

In 1960, Jacques Piccard and Navy Lt. Donald Walsh made history when they descended in the U.S. Navy bathyscaphe Trieste to the bottom of the Mariana Trench. Here, the pressure from the weight of the vast ocean above is over 8 tons per square inch, or the equivalent of an average-sized woman holding 48 jumbo jets!

In 1996, the remotely operated vehicle Kaiko, operated by the Japan Marine Science and Technology Center, visited the Challenger Deep and recorded several marine organisms, including shrimp-like amphipods, a scale worm, a sea cucumber, and various microbes.