Books!One of the most interesting books I've read in quite some time is Blind Descent: The Quest to Discover the Deepest Cave on Earth.
Deep caving, remarkably, is a combination of mountain climbing (in reverse), deepwater diving, and an expedition on Mars. That's how it was described in the book, anyway, and it's a stunning read. As difficult as it is to climb the world's highest mountains, it's even more difficult and more technically challenging to explore the deepest caves. Also, the level of discomfort that must be endured is truly mind-blowing.
The deepest cave (so far) is Krubera (in Georgia, and I don't mean the Peachtree State), is over 7,100 feet and extends for over nine miles. The level of environmental hostility encountered in exploring this beast is carefully documented, as well as parallel (in a literary sense) expeditions in Mexio by U.S. cavers who were (and are) also trying to find the deepest cave in the world.
There's obsession in this story, of course, and madness, and betrayal. A corking good story, in other words, and even more interesting because it's true. If you have any interest in exploration or adventuring, or just want to read a terrifically written book, then hit the link at the top.
People with claustrophobia need not apply.