The greater portion of the Park is in the foothills of Chilean Coastal Range, known as the Cordillera del Piuchén.

It includes zones of dunes, Valdivian temperate rain forests, swamps, and peat bogs.

The climate is wet and temperate, with average annual temperatures of 11 °C (52 °F) and abundant precipitation distributed uniformly throughout the year, varying according to the altitude.

The rainforests are made up of evergreen southern beech (Nothofagus), and some native conifers, including the magnificent alerce (Fitzroya cupressoides).

The park has been designated an Important Bird Area (IBA) by BirdLife International because it supports significant populations of Chilean pigeons, slender-billed parakeets, black-throated huet-huets and chucao tapaculos.