Thermopolis is a mini Yellowstone with a hot spring that pumps out more than 8,000 gallons of water a day which eventually flows over terraces and into the Bighorn River. A square mile of the town is state park - an unusual state park because it encompasses hotels, a hospital and waterparks. The park is free to visit and features paved walking trails, boardwalks and flower gardens. There’s even a free state bath house with a pool of 104 degree water.
The trails and boardwalks are accessible. We didn’t visit the bath house but it’s supposed to be accessible.
RVs can be parked in the large parking lot or on the streets.