Thermopolis Hot Springs

Thermopolis, Wyoming, is home to the world's largest mineral hot spring — Hot Springs State Park's Big Spring — which produces an extraordinary volume of geothermally heated water every day, with temperatures reaching around 54°C as it emerges from the earth. Located in Hot Springs County in central Wyoming, the town and its surrounding state park offer free public bathing facilities alongside private commercial spas and resorts, all fed by the same remarkable thermal aquifer. The bicarbonate-rich mineral waters were considered sacred by the indigenous Shoshone and Arapaho peoples, who ceded the springs to the U.S. government on the condition that they remain freely accessible to all. The dramatic terraced travertine formations deposited by the springs over millennia are a geological spectacle in their own right, set within a landscape of Wyoming badlands and river canyons.