Lechuguilla Cave is, as of June 2013, with 138.3 miles (222.6 km) the seventh-longest explored cave in the world and the deepest in the continental United States (1,604 feet or 489 meters), but it is most famous for its unusual geology, rare formations, and pristine condition.The cave is named for Agave lechuguilla, a species of plant found near its entrance.