Sometimes you have to get below the surface to truly appreciate public lands. Cave systems are fascinating places and can be found at several unique parks across the country. Jewel Cave National Monument in South Dakota boasts over 195 miles of mapped and surveyed passages, an underground wilderness that appeals to human curiosity. The splendor of this hidden gem is revealed through fragile formations and glimpses of brilliant color. Its maze of passages lure explorers, and its scientific wealth remains a mystery. Photo of a lantern tour by Christopher Raborn (www.sharetheexperience.org).