The Puerto Princessa Subterranean River is arguably the world’s most impressive cave-river system. It is possibly the longest subterranean river, and is navigable by small boats through large sections. An extension of the Cabayugan River, it flows through one of the world’s largest cave chambers and ultimately out into the the West Philippine Sea. The caves are part of the Puerta Princesa Subterranean River National Park, which is a UNESCO World Heritage Site.
The area around Puerto Princesa caves has been inhabited since pre-colonial times, and local inhabitants certainly knew about the underground river long before the Spanish showed up in the 19th century. The main level of the river was probably first explored many centuries ago, though it wasn’t until 2010 that other, deeper and largely inaccessible levels were discovered. The national park was established in 1999.
The Puerto Princesa Cave is a limestone labyrinth with about fifteen miles of known passages and a river section of about five miles in length, approximately half of which is navigable. It flows through several huge rooms, including the Italian’s Chamber.
The Puerto Princesa Cave is the most popular natural tourist site on the Philippine island of Palawan. Although visited primarily by residents of the island, it is becoming more popular with visitors from the rest of the Philippines and other countries. The park also encompasses a rainforest with a diverse ecosystem. Web: www.visitpalawan.info (official tourism website).