Into the Lost Crystal Caves
NGC explores one of the world's greatest natural wonders, a massive crystal cave dubbed "Superman's Fortress," which contains magnificent crystals up to 36 feet long and weighing 55 tons. A group of experts enters the cavern, braving temperatures that could kill a human after only 15 minutes of exposure. They'll push their physical limits to explore a crevasse that could lead to another-and possibly more spectacular-crystal cave.