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 .
Gunung Mulu National Park
The national park has three notable caves: Sarawak Chamber, one of the world's largest underground chambers, Deer Cave, the largest cave passage in the world, and Clearwater Cave, the longest cave system in Southeast Asia. The Sarawak Chamber is long, wide and at least high, yielding a volume of and an unsupported roof span of . Meanwhile, the Deer Cave is at to in diameter. As of October 2018, Clearwater Cave has of explored passages.