Popular Hot Springs State Park’s major attraction is undoubtedly its centerpiece, the largest single mineral hot spring in the world. The Big Spring’s steamy mineral water here provides people with a relaxing soak. The water is actually funneled into multiple bathhouses and kept at 104 degrees Fahrenheit. You can kick back in a pair of outdoor pools or visit the popular State Bath House and enjoy the water indoors. Other highlights here include the Rainbow Terrace, the summer flower gardens, petroglyphs, and grazing bison.