Deadly Descent
The deepest caves and the darkest ocean floors remain two of the last undiscovered frontiers on our planet. Caves dangerously twist and turn for miles below the earth's surface, and quietly guard many discoveries, including revolutionary new cures in medicine. But scientists aren't mentally or physically capable of enduring the treacherous underworld of deep cave exploration, which is when elite teams of "cavers" are called upon to undertake deadly descents into mysterious places no other men have ever dared to go before.