Ligawasan Marsh is the largest swamp and marsh area in Mindanao and one of the largest in the Philippines, covering an area of about 288,000 hectares. It is a conglomeration of three marshes: Ligawasan, Libungan and Ebpanan. It is a vast complex of river shannles, small freshwater lakes, ponds, and arable land subject to seasonal flooding in the basin of Mindanao. The area is under water during periods of heavy rainfall. The Marsh is known to support species of endemic threatened birds, including the Philippine eagle and the Philippine duck (Anas luzonica). Because of its relatively expansive swamp forests, it is identified as an important wetland site of many water bird species like herons, egrets, rails, shorebirds and ducks. The Marsh is the last stronghold for the endemic and endangered Philippine crocodile and supports at least 33 species of freshwater fishes. There are 92 species of birds, 6 species of reptiles, 5 species of amphibians.
The floristic composition in the Marsh showed that there are l94 species belonging to l53 genera in 65 plant families. Of these, l2 are endemic to the Philippines. Most of them are upland species, but includes hardwood floral species growing in floodplains.