Challenger_Deep Challenger Deep is the deepest surveyed point in the oceans, with a depth of approximately . The error of measurement is less than a hundred metres. It is located in the Mariana Islands group at the southern end of the Mariana Trench. The closest land is Fais Island (one of the outer islands of Yap), southwest, and Guam, to the northeast. The point is named after the British Royal Navy survey ship HMS Challenger of 1872–76.