In the 20th century, deep-sea exploration advanced considerably through a series of technological inventions, ranging from the sonar system, which can detect the presence of objects underwater through the use of sound, to manned deep-diving submersibles. In 1960, Jacques Piccard and United States Navy Lieutenant Donald Walsh descended in the bathyscaphe into the deepest part of the world's oceans, the Mariana Trench. On 25 March 2012, filmmaker James Cameron descended into the Mariana Trench in , and, for the first time, is expected to have filmed and sampled the bottom.