Evans Plunge in Hot Springs, SD offers natural spring-fed pool and water activity park in the Black Hills National Forest.
Almost more of a tourist 'destination' (I just want to be able to say I swam in the hot springs!), Evans Plunge features water slides (one is 164'), fun tubes, pool games, two childrens pools, traveling rings, sauna, steam room and fitness center.
Evans Plunge does not offer accommodations, but there are a few hotels in the Hot Springs area within a short drive from Evans Plunge.