Puerto Princesa’s pride is easily the Puerto Princesa Subterranean River (or Underground River), a UNESCO World Heritage Site and one of the New 7 Wonders of Nature. The 8.2-kilometer river, said to be the longest navigable underground river in the world, winds its way underneath a mountain range, through the St. Paul Underground River Cave, and then goes out into the South China Sea. The journey through the cave system alone is 24 kilometers long. The entire area where the Underground River is located is actually a national park and a model of biodiversity. More than 800 plant species, including almost 300 trees, 195 bird species, 30 mammals, 19 reptiles, and eight bat species call this area home.