10 U.S. National Parks You’ve Never Heard Of

Wind Cave National Park

Home to the first cave to ever be designated a National Park in the United States, Wind Cave National Park is a shining example of the natural wonders of South Dakota. Notable for it’s displays of the calcite formation known as boxwork, Wind Cave is the most dense (per square mile) cave system in the entire world with more than 140 miles of explored passageways.

Photo: Durant Weston