The Cueva de los Cristales, or Cave of Crystals, is a remarkable cave located in the Naica mine in Chihuahua, Mexico. It is famous for its large selenite crystals, some of which measure over 11 meters in length. The cave was discovered in 2000 and is known for its extreme temperatures, often exceeding 50 degrees Celsius, and high humidity levels. The unique conditions within the cave allowed the crystals to grow to such impressive sizes over thousands of years. The Naica mine itself is a source of lead, zinc, and silver, but the cave's stunning geological formations have made it a point of interest for scientists and tourists alike.