Tolhuaca National Park encompasses part of the forested lower western spurs and foothills of the Andes of the Araucania Region of southern Chile. Adjoining the park to the north is Malleco National Reserve. The park has an elevation of 700 m asl at its western end and 1,821 m asl at its eastern end. It includes small lakes and numerous ponds. Among them are the Laguna Malleco and the Laguna Verde.
The Malleco River's source is located within the park and Tolhuaca Volcano is situated in the vicinity of the park. Park's forests include tree species in pure stands such as araucaria, roble and coihue. Mammal species include the Cougar, Coypu, Chilla and Kodkod.