It looks like Superman's fortress. Hidden deep beneath the surface of the Earth is one of the greatest natural marvels on the planet: a giant crystal cave with crystals up to 36 feet long and weighing 55 tons. But this scorching cavern could kill humans after just 15 minutes of exposure. Follow an international team of scientists as they don high-tech protective gear to safely unlock the secrets of the crystal cave. They'll attempt to answer the questions, What are the crystals made of? How did they reach such superheroic proportions? And is there life here?
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