Underground Emergency...
In one of the world's biggest caves, a scientist g... ...researchers who study caves—are exploring Quankou Dong , or Big Spring Cave, in a remote, mountainous pa... ...typically hidden by clouds.We first went inside Quankou Dong in 2008, after it’d been discovered the ye... ...k at us and smi...
https://www.neatorama.com/2015/03/20/Underground-Emergency/
