The deepest manned ocean descent was achieved by Dr Jacques Piccard (Switzerland) and Lt. Donald Walsh (USA) who piloted the Swiss-built US Navy bathyscaphe Trieste to a depth of 10,911 m (35,797 ft) in the Challenger Deep section of the Mariana Trench on 23 January 1960. Challenger Deep is thought to be the deepest point on earth and is situated 400 km (250 miles) south-west of Guam in the Pacific Ocean (™ Oceans deepest).