Bathyscaphe Trieste
On 23 January 1960, she reached the ocean floor in the Challenger Deep (the deepest southern part of the Mariana Trench), carrying Jacques Piccard and Don Walsh. This was the first time a vessel, manned or unmanned, had reached the deepest known point of the Earth's oceans. The onboard systems indicated a depth of , although this was revised later to ; fairly recently, more accurate measurements have found Challenger Deep to be between and deep.
Chevé Cave
In 2004, an international caving expedition led by the U.S. Deep Caving Team discovered a new cave they named J2. The entrance of J2 located 5 kilometers northeast of the Chevé Cave entrance. J2 appears to head in the direction of Chevé Cave, with a predicted intersection beyond the tunnel collapse that stopped the team in 2003. Current expeditions are underway to find a connection between J2 and Chevé Cave, which will produce a cave system more than 2 kilometers in depth. The integration of the entire system will produce a 2,597 meter deep cave and would represent the deepest cave in the world.