Overview Sunnyside Campground is located along the southeast side of Cougar Reservoir at 1,700 feet in elevation. A large grove of conifers provides shade to these campsites. Motorhomes and trailers not recommended due to the steep entrance into the campground.Recreation Hiking in the area is outstanding in nearby Three Sisters Wilderness, along Rebel Creek. Hikers will enjoy exploring other trails including the French Pete Trail, Box Canyon Trail, Indian Ridge Lookout, and several day hikes