Hornopirén National Park is located in the Andes, in the Palena Province of Chile's Los Lagos Region. The park contains 482 km2 (186 sq mi) of rugged mountains and unspoiled Valdivian temperate rain forests. This national park borders the northern portion of Pumalín Park. The Carretera Austral passes close to the park. In the vicinity of the park lie Hornopirén and Yate volcanoes. The park is dominated by glacier-carved mountains and active volcanoes. It includes glaciers comprising an area of 30 km2 (12 sq mi).
The three main bodies of water in the park are Pinto Concha Lake 4.75 km2 (2 sq mi), Cabro Lake 1.55 km2 (1 sq mi) and Inexplorado Lake 1.5 km2 (1 sq mi). They are surrounded totally or partially by millennial Alerce forests. Inexplorado Lake is one of a series of paternoster lakes that form part of the Blanco River drainage basin. The aforesaid lakes are characterized by distinctive blue and green hues, due to rock flour suspended in their waters and give to the river its milky appearance. Negro River is another major river system in the park.