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.

UENO, Gunma Prefecture--The Fujido limestone cave, which burrows for around 2.2 kilometers and is one of the largest in the Kanto region, has reopened featuring alternating LED lighting.

The clever use of projectors in the room means you feel as if you are really in a dimly-lit cave, and there are animations that bring the ancient paintings to life and explain the stories behind ...