The Wind Cave site is huge. The origin of the name comes from the wind blowing inside the deep and partly unexplored underground cave. The windy phenomenon is generated by the temperature differences between the exterior and the interior of the cavity.
You descend quite deep into the belly of the earth during the visit, and it can be quite cool there.
For the Lakotas this place is sacred, because according to their legend, it is the exact place of their emergence from the underground world to the outside world. For more information, visit the National Park Service web page dedicated to this site: nps.gov/wica/index.htm