Mount Makiling is an inactive volcano rising to 1,090 metres above Los Baños, its lower slopes covered in dense tropical rainforest managed as a natural laboratory by the University of the Philippines. The hike to the summit is challenging — you pass through hot mud springs, river crossings, and primary forest with emergent trees over 30 metres tall. Land leeches are a constant companion in the wet season.
Climbing requires a permit from UPLB and a registered guide. The forest is exceptional for birdwatching — it harbours several endemic Luzon species including the Philippine eagle owl. The hot spring pools on the lower slopes can be reached without climbing to the summit and are accessible for day visitors.