The bathyscaphe Archimède is a deep diving research submersible of the French Navy. It used of hexane as the gasoline buoyancy of its float. It was designed by Pierre Willm and Georges Houot. Archimede was the first vehicle to reach the deepest part of the Atlantic, down into the Puerto Rico Trench. Archimede was christened on 27 July 1961, at the French Navy base of Toulon. It was designed to go beyond , and weighed 61 tons. In October 1961, Archimede passed its first dive tests, diving to unmanned. On 23 May 1962, Archimede descended to off Honshu, Japan, in the Pacific, at the Japan Deep.