Into the Lost Crystal Caves
NGC visits one of the world's greatest natural wonders, a massive crystal cave known as Superman's stronghold, which has stunning crystals up to 36 feet long and weighing 55 tons. A group of scientists braves the cavern's sweltering temperatures, which could kill a human in just 15 minutes. They'll test their physical limits in order to explore a chasm that could lead to another, possibly more beautiful crystal cave.