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.

After getting trapped in a slide in my local McDonald's at five years old, I swore off all tight and dark spaces ... karst ...

and for those who aren't afraid of the dark and want to unleash their inner Lara Croft or Indiana Jones, the Golden State is your go-to for all your cave-exploring, tunnel-trekking, and deserted ...