Firehole River Swimming Area is a 0.1 mile heavily trafficked out and back trail located near Yellowstone National Park, WY that features hot springs and is good for all skill levels. The trail is primarily used for hiking, walking, nature trips, and birding and is accessible from May until October.
Yellowstone National Park PO Box 168 Yellowstone National Park, WY 82190-0168 307-344-7381 (recorded information and an option to speak with someone) Additional info: http://www.nps.gov/yell/contacts.htm
Careful of the "drop off ". Great place to relax and enjoy some warm water. Current can be a bit much for a smaller child though so be careful, it doesn't look as bad as it shows. But either did the drop off which claimed my camera and a story my kids will never forget. Not a hiking trail though, more of a place to relax and enjoy the surroundings. No place else I can compare it to.
A fun place to swim. Usually very busy so finding a parking spot can be difficult
Great place for a swim and stop for lunch. Can be very difficult to find a place to park