Puerto Princesa Subterranean River National Park, also known as Puerto Princesa Underground River, is located around 76 km northwest of Puerto Princesa in the Saint Paul Mountain Range. Named a UNESCO World Heritage Site, it houses a “mountain to sea” ecosystem with some of the most significant and intact old-growth forests in Asia, featuring the spectacular limestone karst landscape and the globally significant habitat for biodiversity conservation and threatened species of wildlife.
There are eight intact forest formations found in Puerto Princesa Subterranean River National Park: the beach forest, forest on ultramafic soil, forest on limestone soil, freshwater swamp forest, lowland evergreen tropical rainforest, mangrove forest, montane forest, and riverine forest. The Palawan Moist Forest, recognised by the WWF's Global Report, is outstanding biodiversity containing the richest tree flora with high levels of regional and local endemism.