The eastern and western sides are bordered by agricultural lands mainly cocoa and oil palm plantations. The terrain within the park is quite rugged and hilly with three main peaks in the form of extinct volcanoes namely:

1) Gunung Magdalena (1,310 m asl),

2) Gunung Lucia (1,189 m asl) and

3) Gunung Maria (1,067 m asl).

The southern perimeter contains some of the last remaining non-swampy land under primary forest in Sabah (Siraj Omar and Jamili Nais, 1995).Seven important rivers with water catchment areas are confined largely or entirely within the park boundary. They are

1) Sungai Tawau and Sungai Kinabutan in the centre,

2) Sungai Mantri and Sungai Balung in the east and

3) Sungai Merotai Kanan, Sungai Merotai Kecil and Sungai Junap (a tributary of Sungai Merotai Besar) in the west.

Sungai Tawau is the main river in the park

An estimated 180 species of birds are present in the park, which makes it an important site for lowland forest species in Sabah especially for hornbills (six species) and pheasants. The Near Threatened Lesser Fish-eagle Ichthyophaga humilis has been recorded as well.