Beneath the Naica mine in Mexico lies a cavern filled with some of the largest natural crystals ever found — towering beams of gypsum in a chamber so hot and humid it can kill. In this episode we venture into the Cave of the Crystals to explore how these giant formations grew over hundreds of thousands of years, why the conditions inside are so deadly, and the race scientists faced to study them before the cave was lost. Discover one of the most spectacular and dangerous places on Earth.

Subscribe for more journeys into the planet’s hidden wonders, and let us know in the comments what we should explore next.