Over colorful terraces along the Big Horn River at Thermopolis flows water from mineral hot springs, over 18,000 gallons every 24 hours at a constant temperature of 135 degrees Fahrenheit. The park has a free Bath House where the water is maintained at 104 degrees for theraputic bathing. Attendants are available to assist you with your needs. The Bath House hours are: Monday - Saturday, 8 a.m. to 5:30 p.m.; Sundays noon to 5:30 p.m. The Bath House is closed on holidays and during the winter and open on holidays during the summer, noon to 5:30 p.m. Hot Springs has 6.2 miles of ADA accessible trail and hiking trail. It is a full-service park with restrooms, Volksmarch trail, fishing and a couple of boat docks and a group picnic shelter that can be reserved.

The terraces were known and used for years by Indians, who believed that the waters were beneficial to health and that they could have a warrior invincible in battle. Chief Washakie of the Shoshone tribe, who built a personal bath house there, and Chief Sharp Nose of the Arapaho tribe sold the hot springs to the United States in 1896 with the provision that a portion should be forever reserved for the use and benefit of the public. Today nothing is left of Washakie's bath house, although a small marker may be found at the site. At Thermopolis each year in early August the presentation of the springs to the white man is re-enacted in the "Gift of the Waters Pageant." When the United States released a one-square mile tract of land to the state in 1897 to establish Big Horn Hot Springs State Reserve, the Reserve became the first of Wyoming state parks. Big Horn Hot Springs still flows over the Rainbow Terraces, but significant additions have been made to the park, including the Wyoming Pioneer Home and the Gottsche Rehabilitation Center where the infirm-both young and old-have the advantage of healing waters. The Plaza Hotel-constructed in 1914, and the Holiday Inn-built more recently, accommodate park visitors, and each establishment owns its own hot mineral water swimming pools are also open to the public. A winding, concrete walkway atop the terraces of sulphurous pools provides a view of algae and mineral formations on the bluffs overlooking the Big Horn River.