For some outdoor adventurers, nothing beats a thrilling, death-defying interaction with nature. This week, we'll show you extreme feats from the outdoor sporting world — at least the ones that were captured on film.
Caving — whether of the extreme variety or not — has a long history. Archaeologists recently discovered ash and charred bone in a South African cave — evidence of a fire set by humans one million years ago . Underground caverns do more than preserve evidence of our ancestors' activities — they support unique ecosystems, which we're only just beginning to chart. Last year, scientists discovered 31 new species in the caves beneath the southern Sierra Nevada.
While some cave routes can be easily navigated by novices, others require spelunkers to climb, twist, and swim through labyrinthian passages. Watch the video below to learn how cavers navigate tight squeezes.
Read more: Jennifer Hattam describes an enchanting encounter with glowworms in New Zealand's Waitomo Caves.
Image from an 1883 geographical publication / courtesy of iStockphoto/whitemay