The park is situated in the rugged Crocker Range that divides the western coastal plains from the rest of Sabah. Crisscrossed by numerous streams and waterfalls, the terrain rises from 300m above sea level to over 2000m and is spread over 139,919 hectares of densely forested terrain. Vegetation is varied, changing with altitude and the park hosts several Rafflesia species.

It is also home to primates such as the orang utan, gibbons and furry tarsiers. Long-tailed macaques, bears, civet cats and wild pigs also roam the park, while hornbills, pheasants and partridges can be spotted flitting between the dense foliage.