In 1948, Swiss physicist Auguste Piccard tested a much deeper-diving vessel he invented called the bathyscaphe, a navigable deep-sea vessel with its gasoline-filled float and suspended chamber or gondola of spherical steel. On an experimental dive in the Cape Verde Islands, his bathyscaphe successfully withstood the pressure on it at , but its body was severely damaged by heavy waves after the dive. In 1954, with this bathyscaphe, Piccard reached a depth of . In 1953, his son Jacques Piccard joined in building a new and improved bathyscaphe , which dived to in field trials. The United States Navy acquired "Trieste" in 1958 and equipped it with a new cabin to enable it to reach deep ocean trenches. In 1960, Jacques Piccard and United States Navy Lieutenant Donald Walsh descended in "Trieste" to the deepest known point on Earth - the Challenger Deep in the Mariana Trench, successfully making the deepest dive in history: .