Located beneath Russia's Ural Mountains, Orda Cave is legendary among divers for its unique beauty. The cave's waters are clearest in winter, when the land above lies frozen. With temperatures approaching minus 40 degrees, NHK attempts to film the cave for the first time ever using 4K cameras. Scientists give them insight into the cave's origins, enabling the crew to uncover the miraculous story of how the cave was naturally formed 300 million years ago by climate change and a shifting landscape.