Puerto-Princesa Subterranean River National Park

The Puerto-Princesa Subterranean River National Park, on the island of Palawan, protects a spectacular limestone karst landscape pierced by one of the world's most remarkable underground rivers. The navigable river winds for several kilometres through a vast cave beneath a forested mountain before emerging directly into the sea, and its lower reaches rise and fall with the tides — an unusual feature that sets it apart from other cave systems. Guided boat tours drift through immense chambers hung with stalactites and alive with bats and swiftlets. Above ground, the park preserves a complete 'mountain-to-sea' ecosystem, from forested peaks and karst cliffs to mangroves and coastline, harbouring some of the most significant old-growth forests in Asia and a wealth of endemic wildlife. Inscribed by UNESCO in 1999 and often counted among the natural wonders of the world, it is one of the Philippines' great protected landscapes.