Yanachaga–Chemillén National Park, National park in Oxapampa Province, Peru.

Yanachaga–Chemillén National Park protects 122,000 hectares of the Yanachaga range in Pasco, from 460 to 3,643 meters. Forest covers nearly all of it except high grasslands; the photograph shows a forested mountain with a rounded summit on the left and a gentler slope to the right, its lower right ridge partly bare and pale green, with tall brown and green grasses in the foreground.

The park was established in 1986 to protect the natural diversity of the region. The forests here are relict from the Pleistocene epoch and survived past climate shifts that converted many forests elsewhere into grasslands.

The Yanesha indigenous people have shaped this region for generations, maintaining deep connections to the forest and its resources. Around the park, Germanic settlers and Andean migrants also live, creating a layered community with different languages, beliefs, and ways of living.

The park's terrain runs from 460 to 3,643 meters, with forested slopes cut by deep canyons on both sides of the Palcazú River. The dry season from May to September is relatively dry, but the cloud forest interior stays cool and wet year-round. Above 4,000 meters, temperatures swing from intense daytime heat to below 0 °C at night.

The frog Ctenophryne barbatula is known only from this park, and the bird list reaches 527 species. The park is also treated as a Pleistocene refuge: forests survived here as isolated remnants while grasslands spread over much of the Amazon basin, which helps explain the number of species packed into 1,220 km².