Remember the Fortress of Solitude from Superman comics and movies? In 2000, miners near Naica, Mexico stumbled upon something miraculous. Near 1,000 feet (over 300 meters) below the surface, where temperatures can reach upwards of 122 degrees Fahrenheit (50 degrees Celsius) with %100 percent humidity, lay a chamber full of giant selenium (gypsum) crystals. The largest measured to date is around 39 feet long (almost 12 meters).
In 2010, a film crew descended to capture the scene for the BBC. Read photographer and camera man Paul Williams’ article about the spellbinding and dangerous experience here. You can also see a clip from the film made in the cave. He had an amazing journey.
Only a few hundred people have entered the Cueva de los Cristales, most with Sinusit respirators and Tolomea suits packed with ice, both made specifically for the cave environment. The heat and humidity are extremely deadly; even equipped properly it becomes unsafe after about 20 minutes, as moisture begins to condense in the lungs. Prolonged exposure leads to suffocation by drowning, followed by baking. Without equipment a person won’t last more than 10 minutes.
Want to learn more? Check out these links:
This article from National Geographic.
This picture gallery from Tourism on the Edge.