[2] It was designated as a Class 1 Protection Forest by the Sabah Forestry Department in 1984.

Gomantong's terrain consists of low to moderate hills and flat areas with swamps.

Swamp species include Mitragyna speciosa and Nephrolepis biserrata.

The reserve hosts numerous Diospyros, Tristaniopsis, Campnosperma, Syzygium and Cordia species.

The reserve is home to orangutan, clouded leopard and wild boar.