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 .
Stephen Alvarez
On another National Geographic assignment Alvarez photographed the deepest cave in the world, Voronya Cave, located 2000 meters beneath the Caucasus Mountains in the breakaway Russian republic of Abkhazia.