Beyond the Deep: Deadly Descent into the World's Most Treacherous Cave

The Huautla Caves system in Mexico has long been the Holy Grail of cavers. Fighting floods, cave-ins and Mazatec Indians who believe the caves are holy, caving teams have competed every year to be the first to prove the cave's depth. No-one has gone further than Bill Stone, the world's foremost caver, whose 20-year obsession nearly ended in disaster.