The Challenger Deep
is the deepest known point in the oceans, 10,924 metres
(35,838 feet) deep at its maximum, near 11° 22'N 142° 36'E.
It is in the Pacific Ocean, off the island of Guam in the Mariana Islands group at the southern end of the Mariana Trench.
The Challenger Deep got its named after the survey ship Challenger II, which was surveying the trench in 1951. In 1960, the US Navy Bathyscaphe Trieste descended to 35,813 feet deep in the trench.
The 35,838 ft. measurement was taken in 1984 by a Japanese survey vessel using a narrow, multi-beam echo sounder.