The cave was discovered thanks to the barometric wind whistling from a blow hole. The wind is caused by the difference in air pressure in the cave and at the surface. Wind Cave National Park is the first cave to be granted the NP designation and it has over 100 mi in passages all contained within 1 square mile area. The tour guide compared it to a bowl of spaghetti.

The cave was our saving grace on a rainy day.

We took two of the three tours offered in May. Imho, Fairgrounds tour is the better of the two.
Fairgrounds Cave Tour – this tour goes through the upper and more impressive level of the cave. There is a number of bigger “rooms” with popcorn, crystal and boxwork formations. Boxwork is a unique formation rarely found anywhere else. You start underground at the elevator and walk up about 90 stairs and another 300 or so down. They call it strenuous but i didn’t think so. There were people of various generations and everyone did it with no problem.

Natural Entrance Cave Tour – starts at the surface, near the natural entrance and goes down about 300 stairs to 225 ft (~70m) underground. You get back to the surface by elevator. Most of the hike is through the middle level, which is a narrow passage most of the way. Still plenty of boxwork, but not as impressive as Faigrounds Tour.