Terwilliger Hot Springs
The USDA Forest Service is much better with words than I am, so here it is, straight from the source:
“As you walk the 1/4 mile trail to this clothing optional hot springs, you are enveloped in the dark hues of primeval woodland, touched by mottled light filtering down from treetops high above and the invigorating scene of the lagoon with the gorgeous Rider Creek waterfall spilling into it.
There are six soaking pools spaced apart by rock walls laid out in steps down a ravine. Temperatures range from 85 degrees in the lower pool to 112 degrees in the upper pool. The pools are 3-12 feet across and an average of 2-3 feet deep. The pool floors are mostly bedrock but some gravel, sand and debris remain at the bottom of the pool.“