For six exciting years Doug Thompson worked as a park ranger at Carlsbad Caverns National Park. In Underground Ranger he passes along the essence of what he learned on this unusual job. He overcame his fear of tight spaces and heights, learned to climb rope, and went on to explore many of the deep vertical caves in the Guadalupe Mountains of west Texas and southeastern New Mexico - including Lechuguilla Cave, one of the most spectacular underground wonders of the world. He even became a member of the park's technical rescue team and made a fifty-story rappel into one of the world's deepest underground pits. He also describes his adventures exploring the surrounding Chihuahuan Desert and shows how caves are related to the earth's surface in a variety of ways, especially through the creative actions of water.