Boybuloq Cave
The cave is the deepest known cave in Asia having been explored to a depth of from the entrance. At the lowest discovered level a water-filled siphon blocks further exploration. It is thought that the cave has the potential to be the deepest known cave in the world, with a theorised depth of making it deeper than the Veryovkina Cave. The explored length of the cave is .
Hellhole
Hellhole is a large and deep pit cave in Germany Valley, eastern West Virginia. It is the 7th longest cave in the United States and is home to almost half of the world's population of Virginia big-eared bats. At 518 feet (158 meters), Hellhole is the deepest of several caves in the Valley.