It all begins with water and rock. As water seeks its level, it becomes acidic. And when it flows over limestone, it etches a path into the rock. Given eons of time, water will burrow and carve, with incredible force, the veins and arteries of planet Earth So the underworld of caves is born. And after torrents have done their work, patient drops do more wonders in a million years or so. Look now on a landscape no one dreamed existed just a few years ago. Here are bizarre and fantastic treasures that stun the eye and strain the imagination. Here is discovery and danger. Here is adventure. In New Mexico, members of a National Geographic Society expedition explore the world's newest and most exotic major cave. They are following one of man's most ancient imperatives to see and understand the unknown. Join us now as we embark on an extraordinary journey deep into the earth to confront MYSTERIES UNDERGROUND. In the Guadalupe Mountains of southern New Mexico, an awesome giant has lain hidden for a million years. Sometimes, in the desert silence, the monster could be heard breathing. The sound came from a yawning chasm in the rocks. In 1986 a trio of weekend explorers broke through a layer of rubble and discovered a new cave only a few miles from famous Carlsbad Cavern.