Lakes Balinsasayao and Danao lie within the Guintabon Caldera on the eastern slope of the Cuernos de Negros volcanic range. Mount Guintabon rises to the west, Mount Balinsasayao to the east, Mount Kalbasaan to the north, and Mount Mahungot to the south -- a ring of peaks that shelters the lakes from wind and development alike. Balinsasayao, the larger lake, spans 76 hectares with a maximum depth of about 90 meters. Danao is more modest at 30 hectares and 58 meters deep. A third, smaller lake called Kabalin-an lies nearby. All three formed in volcanic craters, their waters fed by springs and rainfall rather than rivers.

The twin lakes and their surrounding primary and secondary dipterocarp forests are not just scenery. They function as the watershed for all of southern Negros Oriental, feeding the headwaters of five major river systems -- the Amlan, Ayuquitan, Hinotongan, Okoy, and Cauitan. These rivers irrigate the lowland communities, supply their drinking water, and sustain the agriculture that feeds much of the province. Strip the forest, and you strip the region's water security. The park spans the municipalities of Valencia, Sibulan, and San Jose, and also overlaps with the 133,000-hectare Negros Geothermal Reservation operated by the Energy Development Corporation, where underground volcanic heat is harnessed to generate electricity for Dumaguete and the surrounding region. Protection of this landscape serves both ecological and economic imperatives -- a rare case where conservation and development argue for exactly the same thing.

Birdlife International recognizes Balinsasayao as an important bird area, and with good reason. The park supports at least 114 bird species, including two critically endangered birds found only in this region: the Negros bleeding-heart pigeon, a dove whose crimson breast patch looks startlingly like a wound, and the Visayan wrinkled hornbill, a large, spectacular bird whose numbers continue to decline. The Negros striped babbler, flame-templed babbler, Japanese night heron, and white-throated jungle flycatcher are among the other endangered species that shelter here. Philippine ducks paddle the lake margins. Rufous-lored kingfishers flash through the understory. Celestial monarchs -- small, brilliant blue flycatchers -- dart among the branches. White-winged cuckooshrikes, streaked reed-warblers, Visayan flowerpeckers, and Philippine cockatoos round out an avian community that ornithologists travel considerable distances to observe.

The park's 27 documented mammal species include some of the rarest in the world. Philippine spotted deer browse in forest clearings -- endangered animals found on only a few islands. Visayan warty pigs root through the understory, a species surviving in scattered pockets across the central Philippines. The endemic Negros shrew, found nowhere else, inhabits the forest floor. Visayan leopard cats hunt by night along the ridgelines between the lakes. But the most spectacular mammals take to the air: the giant golden-crowned flying fox, one of the largest bats on earth with a wingspan approaching 1.7 meters, roosts in the canopy alongside the Philippine naked-backed fruit bat, the Philippine tube-nosed fruit bat, and the little golden-mantled flying fox. These animals are not just charismatic. They are seed dispersers whose nightly flights maintain the forest that maintains the watershed that maintains the province.