The Bathala Caves are a series of limestone chambers a few kilometres from Boac, worth visiting for the formations and the sense of exploring something that gets relatively few tourists. The caves contain stalactites and stalagmites, and some of the chambers are large enough to walk through comfortably. Local guides are available at the entrance and are worth hiring — the paths inside are unlit and the guides know the best routes through the system.
The caves take their name from the pre-colonial Filipino word for a supreme deity, suggesting they held religious significance long before Spanish colonisation. Bats roost in the upper chambers and emerge at dusk; arriving in the late afternoon lets you watch them stream out in their thousands. The road from Boac is navigable by motorbike or tricycle.