Mariana Trench
The Challenger Deep has been reached four times by submersibles, namely the manned bathyscaphe Trieste on 23 January 1960, the unmanned robotic deep-sea probes Kaiko (Japanese) in 1995 and Nereus (U.S.) in 2009, and by James Cameron in the Deepsea Challenger on 26 March, 2012. Cameron was able to film a 3D movie of the bottom of the trench.