These caves filled with giant gypsum crystals don't even look real in photographs. They look like someone blew up a photo and then pasted in tiny human images. In these caves, the temperature is 48 C and the humidity is 90%. In other words, they are so miserable that scientists have to wear ice-cooled suits just to get in there. Geologists didn't believe crystals of this size and type were even possible... but there they are.