Jewel Cave National Monumenthttps://www.nps.gov/jeca/index.htm
Beneath the Black Hills of South Dakota lies the fascinating underground world of Jewel Cave. It delights, it perplexes, and it lures you on to further discovery and exploration. Most of the cave's chambers are decorated with calcite crystals and other beautiful, colorful, and rare formations. Caring for Jewel Cave can be a tough job. The National Park Service strives to balance the desire to enjoy the cave with the need to protect it.