The Underground River in Puerto Princesa Palawan is one of the longest and most visited national park in the Philippines. It is one of the most important protected areas in the Philippines and is designated as a core area of Palawan biosphere reserved.

It was established as the St. Paul Subterranean National Park on March 26 1971 by virtue of Presidential Proclamation 853. It was created primarily to protect and preserved the outstanding biophysical properties of the area.However studies later concluded that the size was not sufficient to ensure the long-term viability of the park. This was resolved by the signing of the Presidential Proclamation 212 on November 12 1999. The said proclamation amended the park boundary to include community buffer zones and changed its name to Puerto Princesa Subterranean River National Park to properly identify it with the area.

The park is best know for the existence of an intensive underground river system. It also protects significant old growth tropicals considered by experts to be among the most biologically diverse ecosystem in the world. So far more than 800 plant species have been identified including some 295 trees dominated by the dipterocarp type birds 30 species of mammals 18 species of reptiles 10 species of amphibians and a large number of insect species.In recognition of its high conservation value the United Nations Educational Scientific and Cultural Organization has inscribed the park to the list of World Heritage Site

The park is managed by the government of Puerto Princesa under a program of sustainable development centered on environment. It is being managed by the city through multi sectoral Protected Area Management Board or PAMB.