One of the favorite family spots in town is the Evans Plunge Indoor Pool and Mineral Spa (1145 N. River St., 605/745-5165, www.evansplunge.com, open year-round, hours vary seasonally, adult $11, child $9, free for child under 2). The Evans Plunge, a 50-by-150-foot gravel-bottomed mineral pool, came into being at a time when mineral springs were believed to have great medicinal value.

Doctors recommended that patients drink mineral water to cure all kinds of internal ailments and prescribed soaking in it to cure joint problems. The warm mineral springs cure has been with us almost as long as recorded history.

That all changed with the creation of synthetic drugs in the 1930s. Why travel uncomfortably for hundreds of miles when a cure is waiting in your bathroom medicine cabinet? And so began the slow decline in medical tourism.

There are whispers that old-fashioned pools like the Evans Plunge have no future in the highly competitive water-park market of the 21st century. But that would be unfortunate. The inside of the Evans Plunge today looks much as it did 100 years ago. The water is crystal clear since the spring-fed pool has a complete change of water 16 times a day. Very little chlorine is needed in the pool because of the constant water change. No chlorine smell, no burning red eyes.

The Plunge today has two water slides, a set of rings to swing out over the pool, basketball hoops, alligators and rafts to float on, a children’s shallow pool, a small outdoor pool, and a great mural of the Mammoth Site painted on the wall. The gravel bottom is a refreshing change from the bright aqua color of most standard swimming facilities. There are life guards on duty at all times. The pool is big enough for the kids to have a great time and small enough to keep an eye on them.

The first amenity at the site where the Evans Plunge now stands was a bathtub-like structure picked out of the rock about three feet wide by three feet deep and eight feet long. Guests generally brought their own towels and accommodations included a tent by the side of the spring. The original soaking site was outdoors.

In 1891, Fred T. Evans, one of the original founders of Hot Springs, opened the luxurious Evans Plunge complex. Unlike most of the bathhouses of the time, which were somewhat serious institutions of healing, Evans built the plunge with slides and rafts for guests to enjoy. Over time, the original wood frame building had to be replaced as the damp and warped rafters surrendered to the wet environment; today, the exterior of the plunge is a rather uninteresting concrete block. But inside, the slides, the rafts, and the fun remain.

Use of the health club, which includes free weights, exercise equipment, hot tubs, and a sauna is an additional $3.50.