Wyoming's oldest state park features massive geothermal springs, cascading travertine terraces, a free public bathhouse, and a resident bison herd.
Hot Springs State Park, located in the central Wyoming town of Thermopolis, is defined by the mineral tang of sulfur and the constant plumes of steam rising from the Big Spring. This geothermal feature is a massive, primal gush of superheated water, surging from the earth at a constant temperature of roughly 128 to 135 degrees Fahrenheit. Especially on cool mornings, the steam billows thick and heavy, creating a dense veil over the vibrant landscape of the Rainbow Terraces. These travertine formations glow with shades of orange, yellow, and green, stained by thermophilic algae and minerals, forming a living, cascading sculpture where the mineral-rich water pools and eventually empties into the Bighorn River. It is a sensory experience that immediately grounds visitors, serving as a physical reminder of the powerful geothermal forces at play beneath the Wyoming crust.
The source of this spectacle lies deep underground, where ancient geological pressures heat groundwater before it surges upward. Laden with dissolved calcium carbonate, the water cools upon reaching the surface, depositing minerals that slowly build the intricate travertine formations. Historically, these springs were sacred to the Eastern Shoshone and Northern Arapaho tribes, who recognized their healing properties and referred to the area as the Warm Valley. The Shoshone called the smoking water Bah Guewana. In 1896, facing immense economic hardship, the tribes agreed to cede a 100-square-mile portion of their reservation to the federal government for $60,000. Chief Washakie of the Eastern Shoshone famously agreed to the transaction under one strict condition: the waters of the main spring must remain free to the public forever. In 1897, the federal government released a one-square-mile tract to the state of Wyoming, creating the state's very first state park, initially known as the Big Horn Hot Springs State Reserve.
Today, the park honors Chief Washakie's treaty terms at the Wyoming State Bath House, where visitors can soak in the therapeutic, mineral-rich waters cooled to a comfortable 104 degrees Fahrenheit. Beyond the bathhouse, visitors can wander the boardwalks directly over the active travertine formations or cross the Bighorn River via the historic suspension footbridge, commonly known as the Swinging Bridge, which offers views of the river and the colorful mineral terraces. The park is also home to the official State Bison Herd, a lineage established here in 1916. Maintained at around 15 animals to match the carrying capacity of the local pasture, these massive animals can be viewed safely from vehicles along Pasture Road, particularly during the late fall and winter months when they gather for their daily 8:30 a.m. feeding. Every year during the first full weekend in August, the local community and tribal members gather on the lawn by the Big Spring to perform the Gift of the Waters Pageant, a historical commemoration of the 1896 treaty that keeps the spirit of the springs' origin alive.
To soak in the free State Bath House, remember to bring your own towel and swimsuit. Soaks are strictly limited to 20 minutes per visit for health and safety reasons, though you can return after a two-hour break. To see the bison herd up close, drive along Pasture Road around 8:30 a.m. during late fall or winter when park rangers feed them a daily supplement.