It is believed that the earth's deepest point under water is to be found off the coast of the island of Guam, in the Pacific Ocean.

The trench, (also called the Marianas thench, in reference to the islands nearby or also the Challenger Deep) is believed to be 120 times larger than the Grand Canyon and 1.6 km deeper than the height of Mount Everest.

It was in 1960 that US navy-owned bathyscaphe Trieste reached the depth of 35,800 feet, as part of the project Nekton.