Into the Lost Crystal Caves
NGC takes viewers inside one of the world's greatest natural wonders - a massive crystal cave dubbed Superman's stronghold, complete with stunning crystals measuring up to 36 feet in length and weighing 55 tons. A team of experts enters the underground, braving temperatures that might kill a human after only 15 minutes. They'll defy physical limitations in order to investigate a chasm that may lead to another-and probably more magnificent-crystal tunnel.