Mount Thielsen lies in the southern section of the Mount Thielsen Wilderness, which is part of the Deschutes, Umpqua and Fremont-Winema national forests. On the west, the wilderness borders the Oregon Cascades Recreation Area, a area set aside by Congress in 1984. The wilderness and forests offer several activities related to the mountain, such as hiking and skiing. The wilderness covers around the volcano, featuring lakes and alpine parks. It also contains of the Pacific Crest National Scenic Trail, accessible from a trailhead along Oregon Highway 138. In 2009 the trail was selected as Oregon's best hike. Three skiing trails exist on the mountain, all of black diamond rating. They follow several trails through the wilderness from the bowl of the mountain.