Hot Springs State Park

In 1897 the springs at Thermopolis became the Big Horn Hot Springs State Reserve, Wyoming's first state park. The water comes out of the ground at around 130 degrees and spreads across the Rainbow Terrace, a sheet of travertine that runs along the Bighorn River for about a thousand feet, banded white, yellow and brown where minerals settle out as the water cools. Smaller springs, White Sulphur and Black Sulphur among them, run out of the old travertine elsewhere in the park on their way to the river.

The Swinging Bridge, a suspension footbridge first hung across the river in 1916 and rebuilt in 1992, is the best place to see the terrace whole. Bison have lived in the park since 1916, and a herd of about two dozen ranges over the hill above a loop road; in winter they are fed in the mornings, and visitors watch from their cars.

The park charges nothing to enter, and neither does the State Bath House inside it, where the spring water is cooled for bathing; two commercial pools nearby charge admission. The park also manages the Legend Rock petroglyph site northwest of town.