The park protects the body of Todos los Santos Lake and a large part of its catchment. The outlet of the lake at the Petrohué locality gives rise to the Petrohué River. A short distance downstream, still within the limits of the Park, the Petrohué river flows through the Petrohue Waterfalls. The Park also contains the eastern slope of Volcan Osorno, the southern slope of the Puntiagudo and the western slopes of the Tronador, with a maximum altitude of . These mountains with year round snow give a strong imprint to the landscape.