Carlsbad Caverns National Park

As you pass through the Chihuahuan Desert and Guadalupe Mountains of southeastern New Mexico and west Texasófilled with prickly pear, chollas, sotols and agavesóyou might never guess there are more than 300 known caves beneath the surface.The park contains 113 of these caves, formed when sulfuric acid dissolved the surrounding limestone, creating some of the largest caves in North America. This includes Lechuguilla Cave, the nation's deepest limestone cave at 1,567 feet (478m) and fourth longest.