2. Jewel Cave National Monument – South Dakota
With a name derived from the delicate crystals that line its walls, Jewel Cave National Monument is like a treasure chest waiting to be explored.
With over 177 miles of charted passageways, Jewel Cave the third longest in the world.
Choose from the Scenic Tour ($12 adults, $8 ages 6-16) for a trek through an underground menagerie of stalactites, draperies, cauliflower and flowstone formations, or the Historic Lantern Tour for a 1940’s style experience on an unpaved path lit only by hand held lanterns
For more adventurous types, the Wild Caving Tour ($31 for adults, no children under 16) takes you on a multi-hour adventure that will have you scaling rocks via ropes and crawling through nearly a mile of this massive underground world.