Criterion (vii): The Puerto-Princesa Subterranean River National Park features a spectacular limestone or karst landscape. It contains an underground river that flows directly to the sea. The lower half of the river is brackish and subject to ocean tide. The associated tidal influence on the river makes this a significant natural phenomenon. The river’s cavern exhibits dramatic speleothems and several large chambers of as much as 120m wide and 60m high. Its accessibility and navigability up to 4.5km inland allows it to be experienced by the general public, who can view the magnificent rock formations on a river cruise unequalled by any other similar experience elsewhere in the world.