Terwilliger (Cougar) Hot Springs in Willamette National Forest

Terwilliger Hot Springs, almost universally called Cougar Hot Springs after the nearby reservoir, is one of the Willamette National Forest's signature destinations. Four soaking pools step down a ravine, separated by stacked rock walls, with water cooling from around 112 degrees in the uppermost pool to roughly 85 degrees at the bottom. The setting, a quarter-mile from Forest Road 19 along the Rider Creek Trail, is classic western Oregon: ferns, mossy old-growth, and filtered light.

The Forest Service runs Terwilliger as a day-use, fee site open from sunrise to 10 p.m. The bathing area is clothing-optional, though nudity is not permitted within view of the Aufderheide Scenic Byway. Reservations are not part of the system here; the fee is paid on site. Because Forest Road 19 is not maintained for snow and ice in winter, the easiest visits come when the byway is clear.

Cougar Hot Springs sits in the heart of McKenzie River and Aufderheide Scenic Byway country, a region built for RV touring. Reservoirs, old-growth trails, and the McKenzie's blue-green water are all within a short drive, so a rented camper turns a single soak into a layered Cascades loop. Eugene makes a logical launch point about 53 miles to the west.