Underground River in Philippines

The Puerto Prinsesa Underground River in Palawan, Philippines is known as  the longest navigable underground river in the world. It is an 8.2-kilometer river winding beneath a mountain range. It is passed through the St. Paul Underground River Cave which opens to the the South China Sea, where it empties out. To journey through the entire cave system you could 24 kilometers through the subterranean realm. Introduced as one of the New 7 Wonders of Nature, the Underground River boasts of stunning cave interiors: enormous stalagmites and stalactites, the 360-meter-long cave dome, subterranean waterfalls, a water hole, and numerous endemic island flora and fauna. Because of its exceptional and special beauty, it was also named as one of UNESCO’s World Heritage Sites in 2004. The cave has still not been explored completely since deeper areas are deprived of oxygen, to this day. To find  this Underground River, visitors must hike from the nearby town of Sabang to the National Park underneath the Saint Paul Mountain Range 50 kilometers north of the Palawan capital.