Wind Cave National Park

Wind Cave National Park is an American national park located 10 miles north of the town of Hot Springs in western South Dakota. Established on January 3, 1903 by President Theodore Roosevelt, it was the sixth national park in the U.S. and the first cave to be designated a national park anywhere in the world. The cave is notable for its calcite formations known as boxwork, as well as its frostwork. Approximately 95 percent of the world's discovered boxwork formations are found in Wind Cave.

Wind Cave is one of the best known examples of a breathing cave. The cave is recognized as the densest cave system in the world, with the greatest passage volume per cubic mile. Wind Cave is the seventh longest cave in the world with 154.2 miles of explored cave passageways and the third longest cave in the United States, though it is only the second longest cave in Custer County, South Dakota behind Jewel Cave.