At 1,966 m, Mount Isarog is southern Luzon's highest forested
peak - an andesitic stratovolcano that fills the entire isthmus between
Lagonoy Gulf to the east and San Miguel Bay to the northwest. Its
summit is the point where seven local governments meet: Goa, Tigaon, Ocampo, Pili,
Naga City, Tinambac and Calabanga. PHIVOLCS still classifies Isarog as active, but
its only known Holocene activity - explosive eruptions and pyroclastic flows tied to a
lava-dome collapse - dates to roughly 3500 BCE, about 5,500 years ago. The
2,500-m-wide summit crater is long since breached to the east, its floor drained by the
Rangas River; the Maalsom vent still seeps gas and feeds warm springs
near the rim.
Declared a forest reserve in 1935 and a national park in 1938, Isarog was
re-classified a protected Natural Park in 2002 (10,112 ha). Its mossy upper
forest, wrapped in cloud for much of the year, is the only known home of three small
mammals: the Isarog shrew-rat, the Isarog striped shrew-rat and the
Isarog shrew-mouse - alongside the Isarog forest skink, 15 Luzon-endemic
birds, and stands of Rafflesia, the world's largest flower, among 1,300-plus
plant species. Press the button below to draw the mist up through the canopy.
The main route up, the Panicuason Trail, climbs east of Naga City past
Malabsay Falls - a broad, popular cascade with a swimmable lagoon - and
Nabuntalan Falls further upslope; the WWII-era Guerrilla Caves near
Panicuason recall the mountain's use as a resistance hideout. On the Pili flank,
Balang Falls drops through Barangay Curry. Sixteen rivers born on Isarog's
slopes supply potable water to fifteen of Camarines Sur's thirty-five towns and
irrigate some 67,400 ha of ricelands below. Terrain is real NASA SRTM elevation draped
with Esri World Imagery; the crater and summit forest are refined with a denser mesh
and z15 imagery.