From www.ganoksin.com: "Mexico's Cueva de los Cristales (Cave of Crystals) contains some of the world's largest known natural crystalstranslucent beams of gypsum as long as 36 feet (11 meters). How did the crystals reach such superheroic proportions? National Geographic writer Neil Shea and photographer Carsten Peter discuss the extreme working conditions inside Mexico's Cave of Crystals."
It looks like a scifi scene. Prepare to be amazed.