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