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.
Neffs Cave
In 1952 the Salt Lake Grotto of the National Speleological Society was established, and several weeks later the grotto's members obtained permission from the National Forest Service to explore the cave. They spent nearly eleven hours in the cave but had not reached the end of the main passage before they had to turn back. Teams from the grotto returned in 1953 and 1956, and in the last visit they succeeded in reaching the bottom of the main passage. They calculated a vertical depth of 1186 feet (361 meters), which was later revised to the present figure of 1163 feet (354 meters). Neffs Cave is the 13th deepest cave discovered in the United States.