A jungle inside a cave? A roof collapse long ago in Hang Son Doong ... Stands of bamboo and other vegetation cover mounds of limestone here, making the place all but impenetrable.

Most Route 66 motels just offer a bed and a shower. Grand Canyon Caverns Inn threw in a limestone cave system, the deepest ...

After the disturbances, biologists from the National Park Service, U.S. Fish and Wildlife Service and the Nevada Department of Wildlife counted only 38 fish this spring in the limestone cavern ...

Lechuguilla Cave at Carlsbad Caverns is the deepest limestone cave in the country, and the fifth-longest known cave in the world. Read more about Oil and Gas Development Delayed Near Carlsbad Caverns ...

Clip: Under most of Florida is a limestone bed ... a cavern forms. When the cavern gets too big, the ground above it collapses, dragging a typically circular section of the Earth's crust down ...