Hang Son Doong (Mountain River Cave) in Vietnam

An evening pause: As I have been out today doing survey work for a cave project of which I am the cartographer, I thought this video of Hang Son Doong (Mountain River Cave) would be appropriate.

Note that this cave is definitely not the largest in the world, as is often claimed. It appears to have the largest single room of any known cave, but the cave itself is relatively small at about four miles, compared for example to Mammoth Cave in Kentucky, which is the world’s longest cave at 400 miles.