Located in the San Martín Region of Peru between the Marañón and Huallaga rivers, the park has an area of approximately 2,745.2 square kilometres.

The montane cloud forest, composing most of the park area, is a high-altitude rainforest with short trees, moss and lichen.

The yellow-tailed woolly monkey, Oreonax flavicauda, previously thought to be extinct, is known to live in the park and appears to be endemic to the region.

The most famous archaeological site in the Rio Abiseo park is Gran Pajatén, a ruined settlement atop a forested ridge overlooking the Montecristo River canyon.

Gran Pajatén, Los Pinchudos and other archaeological remains identified in the park are usually attributed to the Chachapoyas culture.