Crystal Cave of Giants Naica, Mexico - Sept 3 - 6, 2009 Air Temperature of 50C(122F) + Relative Humidity of over 90% = Humidex Value of 105C (228F) !! This is one of the most extreme places on the planet. The Crystal Cave of Giants was accidentally discovered in 2000 by miners working in the silver and lead mine at Naica, Mexico. It lies almost 300 meters (900 feet) below the surface of the Earth and it contains the largest crystals known in the world, by far. The largest crystals are over 11 meters long (36 feet) and weigh 55...