The Lake Castrovalva area of Lechuguilla (cave) in Carlsbad Caverns National Park, New Mexico, is very special. It is abundant in very delicate and unique cave formations, and for this reason it is very rarely visited. These formations are simply perfect and pristine. Here, a geologist admires a fine set of rimstones and gours. For millions of years, the cave has been sealed off from human and animal interaction. The cave is so beautiful and so important to science that access is strictly controlled in order to keep the cave in as pristine condition as possible. It is a real time machine, taking us back to a world that was very different to the one we live in today.