The park has been protected since 1943 and was declared a World Biosphere Reserve in 1977 ensuring the integrated protection of it fauna and flora.

Although only 10,000 hectares in size, it preserves an almost entirely intact semiarid community largely unique to north-central Chile; it also includes a relict fog forest on coastal ridges which gives the park its name. 

Many plants and animals in the park are rare to absent outside, and there is a diverse assemblage of small mammals, vertebrate predators, plants, and other components of undisturbed semiarid communities here.  This makes the park a remarkable living laboratory for studying the role of abiotic factors related to rainfall as well as biotic interactions among the many components.

Fog forest

Park entrance

Thorn scrub habitat