Comprising an area of 107,000 hectares, the landscape of the park has been molded by intense volcanic activity and the shaping action of glaciation. The highest peaks are the Casablanca and Puyehue volcanoes, and the Caulle mountain range.

The climate of the park is temperate and rainy, with a high level of precipitation between March and September. On the high ground there is snow in winter and spring. The main river is the Golgol, with its tributaries, which runs into the Lago Puyehue. Other lakes of importance include Constancia, Gris and Paraíso.

The vegetation varies with the altitude, although the underbrush is always abundant, made up of ferns, shrubs, moss and lichens. In the lowest areas there are forests of coigüe and ulmo. In the higher areas of the park coigüe, tepa and manío are the principal species.

The fauna is equally important in the national park. Among the wildlife are the puma, the gray fox, the quique or ferret, the coypu, the wild cat and the skunk.

The trails that you can follow are organized around three areas: Aguas Calientes, Antillanca (also a ski center) and Anticuar.