The deepest part of the ocean is called the Challenger Deep, and it is located in the Mariana Trench in the western Pacific Ocean. The Challenger Deep reaches a depth of approximately 36,070 feet (10,972 meters). It was named after the HMS Challenger, a British survey ship that conducted the first scientific survey of the trench in 1875. The extreme depth of the Challenger Deep poses significant challenges for exploration and has only been reached by a few manned and unmanned missions.