It is a mountainous region in the Tanaoan Ridge within the Mount Zamal Range that divides the three provinces of Samar.

[1] It consists of old growth trees and a system of rivers, waterfalls and streams capable of generating 2,279 liters per day.

1158 issued by President Fidel Ramos, the watershed was reclassified as a protected landscape.

The area is the location of all three sources of water supply for the Calbayog City Water District, namely Pan-as Falls in the barangay of Pilar, and Pasungon Falls and Himoni River in the adjacent barangay of Cabatuan.

[7] It is surrounded by open canopy and residual forests with some areas of cultivation with brushes and grasslands.