The Puerto Princesa Underground River is today the main attraction for local and foreign tourists visiting Puerto Princesa. It is believe to be one of the longest navigable underground rivers in the World which features cathedral-like caverns and domes. The stalactites and stalagmites formation resembles like religious images, fruits and birds.

The Underground River is located in the Puerto Princesa Subterranean National Park (PPSRNP). The Park features an 8.2 km Underground River that flows beneath a spectacular limestone or karst formation before directly emptying into the sea.

The PPSRNP is only one of the very few places in the world where a full mountain to sea forest ecosystem still exists. The Park is a declared World Heritage Site, and was proclaimed a Philippine National Park in March 1971 under a Presidential Proclamation.

The National Park attracts annually more than 60,000 visitors and is located in the West Coast of Palawan, 81 km north of Puerto Princesa City. Various joint endeavor have been done so far between and among government and non-government organizations including the community surrounding the Park to improve the services to visitors who frequent to the Underground River when they are in Puerto Princesa.

The Park is also a popular destination for visiting bird-watchers. Most of the threatened and restricted range birds of the Palawan Endemic Bird Area have been recorded here. Several threatened species are regularly seen in the extensive lowland forests and substantial number of Palawan Phesant Peacock and Philippine Cockatoo are found in the park. Other birds of the area the Malcoha, Heron, Kingfisher, Hornbills, Sea Eagle, Parrots and others.

The land form in the park is associated with rocky mountains (marble and limestone) running from north to south. Two-thirds of the area is covered by lush tropical rainforest from the shoreline to the highest peak, and one-third is thinly vegetated karst limestone. The vegetation types include lowland forest ,coastal forest and karst forest.

The highest point of the park is the Mount St.Paul, which is 1,028 meters (m) above sea level.