Agusan Marsh is one of the most ecologically significant wetlands in the
Philippines - a 15,000-hectare complex of freshwater swamp forest, watercourses and some
59 shallow lakes in the upper basin of the Agusan River, ringed by the
hills of eastern Mindanao. It holds close to 15% of the nation's freshwater resources and
was declared Ramsar Wetland No. 1009 in 1999 and ASEAN Heritage Park No. 42
in 2018.
It breathes with the seasons. Sitting in a natural basin barely 20 m above the
sea, the marsh gorges on the monsoon: water floods in between October and February and the
wetland swells to several times its dry-season size, then drains away by summer. Drag the
Flood season slider to raise and lower the water - from dry-season channels and
open lakes to the peak flood that drowns the basin floor. The Agusan Manobo live
with this rhythm in floating villages of bamboo and nipa lashed to hardwood logs that rise
and fall on the water, at lakes such as Panlabuhan in Loreto and
Mambagongon in La Paz.
The marsh is a stronghold for water birds and for two crocodile species. In a creek near
Bunawan in 2011 villagers caught Lolong, a 6.17-m saltwater crocodile -
the largest ever measured in captivity.
Built live in your browser from real data: NASA SRTM elevation (Mapzen terrarium tiles
from AWS) decoded pixel-by-pixel and displaced at true horizontal scale, draped with Esri
World Imagery. The flood is modeled hydrologically - the water rises and falls over the
real basin heightfield, so it fills the lowest channels first and spreads across the floor
as the level climbs.