It occupies an area of 786.04 hectares (1,942.3 acres) of grasslands and old-growth forest in northern Bataan province near Olongapo and the Subic Bay Freeport Zone.

567 signed by Governor-General Theodore Roosevelt Jr.[3][4] In 1965, the national park was reduced to 1,334 hectares (3,300 acres).

Subic–Clark–Tarlac Expressway (SCTEx) and Jose Abad Santos Avenue (also known as Olongapo–Gapan Road) traverse the southern part of the protected area with the Tipo Toll Barrier that connects SCTEx to the Subic Freeport Expressway close to park's southwestern edge.

It is composed of 87% grassland dominated by cogon and talahib, and 13% remnants of old growth forest and mahogany and teak plantations.

[6] The park is a habitat for several endangered species and game animals which include pythons, monitor lizards, cloud rats, quails, kingfishers, flycatchers and fruit bats.