A short hike through some mossy woodlands near Cougar Reservoir will take you straight to the Terwilliger Hot Springs.
These are well-loved, natural hot springs that surface close to the Mackenzie River. Fed from subterranean waters heated by their journey along channels deep in the Earth, there are springs total. They flow from a cave source, fed by the same stream, and each of these successive hot springs is slightly cooler than the one above it. Another nearby surface stream offers visitors a reprieve if they become overheated.
Terwilliger Hot Springs are clothing optional, but visitors are asked to stay clothed until they reach the pools. Note that it’s common to see bathers making use of this freedom. Alcohol and glass are banned from the site, which is well-maintained and includes facilities including restrooms and hiking gear storage space.
The cost to visit the pools is $6 per person, which can be paid to the attendant at the trailhead. Note that the pools are drained and cleaned weekly on Thursday mornings before 11 a.m., and are often closed before that hour.
Directions from the U.S. Forest Service:
From Blue River, OR, travel 4 miles east on Highway 126 to Aufderheide Drive (Forest Road 19).
Continue on south Aufderheide Drive, taking a right at the Y to the top of Cougar Reservoir. Continue south on Aufderheide Drive for 5 miles to Terwilliger Hot Springs parking lot.
Hike 1/4 mile west on Rider Creek Trail #3319 to Terwilliger Hot Springs.