Beneath the Earth’s surface lies a world so extreme and isolated that it seems more like an alien planet than part of our own. Veryovkina Cave, the deepest known cave on Earth, plunges a staggering 7, ...

Don, 64, was a guide at Mammoth Cave for 10 years and spent 18 winters on the legendary expeditions that helped expand the map of Chevé in Oaxaca, Mexico, the second deepest cave in North America.

Krubera Cave in the republic of Georgia is currently the deepest known cave, at 7,208 feet. But Dark Star, with so many areas still to survey, is a prime candidate to take over the title.

The park contains over 85 known caves. This includes Lechuguilla Cave, the nation's deepest limestone cave at 1,567 feet (478m) and third longest . Life in the park includes approximately 750 ...