Jacques Piccard (28 July 1922 – 1 November 2008) was a Swiss oceanographer and engineer, known for having developed underwater submarines for studying ocean currents. In the Challenger Deep, he and Lieutenant Don Walsh of the United States Navy were the first people to explore the deepest known part of the world's ocean, and the deepest known location on the surface of Earth's crust, the Mariana Trench, located in the western North Pacific Ocean.
Source : Wikipedia
