San Marcelino

San Marcelino is a town of the province of Zambales in the Philippines. Situated at the foot of the Mount Pinatubo massif, it combines indigenous Aeta heritage and natural wonders within its territory, despite challenges brought by the Mount Pinatubo eruption in 1991.

San Marcelino was established by the Spanish in the mid-19th century. Its original inhabitants where the dark-skinned Aetas, who continue to farm in the slopes of the Zambales Mountains and Mount Pinatubo. It is one of two landlocked municipalities in Zambales, the other being the neighboring Castillejos to the south.

In 1991, the town was devastated by ashfall caused by the eruption of Mount Pinatubo, just northeast of the town. Pinatubo further inflicted misery on the town as it filled the Santo Tomas River with lahar, burying villages under volcanic mud. Despite this, San Marcelino recovered as displaced residents were resettled in planned communities.

San Marcelino lies along the Olongapo-Bugallon Road (Route 306), the main thoroughfare in Zambales. A junction at the downtown, between the municipal hall and 7-11, leads west towards San Antonio.

It is accessible by bus from Metro Manila, with Victory Liner passing by the town as part of their frequent daily trips to the provincial capital, Iba, immediately to the north, or to Santa Cruz. An alternative option is to switch to jeepneys or passenger vans in Olongapo, where such buses make stopovers.

Tricycles are the main mode of transportation between barangays.

• 15.144976120.3494041 Mount Pinatubo. Inevitably associated with the town, the volcano is the biggest draw in the area, particularly its crater lake and the lunar landscapes created along its gullies following the 1991 eruptions.  (updated Aug 2026)
• 14.984348120.2943162 Mapanuepe Lake. A large reservoir formed when lahar flows from the Mount Pinatubo eruption dammed the Mapanuepe River, a tributary of the Santo Tomas, and submerged an eponymous village, displacing thousands of residents. The lake is now a popular fishing and recreationally area, although it is also claimed to be home to a local version of the Loch Ness Monster.  (updated Nov 2026)
• 15.033120.1801133 Mount Pimmayong, Santa Fe. A 657 metres (2,156 ft) high peak with views reaching up to Subic Bay and the South China Sea.  (updated Nov 2026)
• 15.00668120.2518184 Mount Bagang, Santa Fe. A mountain that was reduced into a 302 metres (991 ft) high hill when lahar flows from Mount Pinatubo filled up the surrounding Santo Tomas River and raised the ground by hundreds of meters.  (updated Nov 2026)
• 15.026626120.329415 Mount Balitog, Aglao. A 1,057 metres (3,468 ft) high peak overlooking Mapanuepe Lake.  (updated Nov 2026)

As a landlocked town on the Zambales mountains, San Marcelino is a prime destination for hikers and the volcanologically inclined, with the lunar landscapes of what remains of the Santo Tomas River valley being an alternative to those unable to hike the top of Mount Pinatubo itself. There are also opportunities to visit indigenous Aeta communities along the way.

• 14.974816120.1563441 San Marcelino Public Market, Olongapo-Bugallon Road, Central.  (updated Nov 2026)

Climbing Mount Pinatubo and other mountains in the area is not for the faint hearted. Permits are required to undertake the hike, and will only be given to those with climbing experience. It is best to arrange such trips with a reputable tour operator.

During the rainy season, flooding, mudslides and lahar flows from Mount Pinatubo are common along the Santo Tomas River basin.

The indigenous Aeta communities still adhere to their precolonial customs and belief systems and are widely respected even by the non-Aeta resident population. As they are the most experienced in dealing with the natural settings of San Marcelino, you are expected to exercise maximum respect for their traditions and when visiting them.

Since 2025, some highland sites along the Pinatubo trails may be closed due to ongoing disputes over custodianship and administration between the Aeta communities and the local government, which has led to some blockades by Aetas.

The town's postal code is 2207.

Iba ← San Narciso ←

N  S

→ Castillejos → Olongapo