Puerto Princesa - a secret underground river in the Philippines

Deep underground on the island of Palawan in the Philippines lies the Puerto Princesa Subterranean River National Park. Both a UNESCO World Heritage Site and one of the New 7 Wonders of Nature, it’s the world’s longest navigable underground river and makes for an exciting experience in one of the Philippines’ most popular islands. Here’s everything you need to know about exploring the Puerto Princesa Underground River.

Where is the Puerto Princesa underground river?

The river flows directly underneath the St Paul Mountain Range, found on the mid-western coast of Palawan island. The river system was created millions of years ago as water channelled its way through the rock creating a series of vast chambers and caverns.

The cave system stretches for a total of 24km beneath the mountains. Visitors can explore a smaller portion – entering the cave from the point where the underground river reaches the sea.

The river and caves are home to a complex ecosystem that has adapted to the underground conditions over hundreds of years. Many of the species found in the caves are endemic to the river system, including certain types of giant spiders, crabs, fish and snakes, although bats and swallows are likely to be the only creatures you’ll see.

Visiting Puerto Princesa

A trip to the subterranean river national park is absolutely worth the effort if you're visiting Palawan. It's an otherworldly experience as you paddle through the dark. The clicking of bats and the echoing drips of water are the only sounds you hear. You'll glide through cavernous rock cathedrals and past stalactites into the centre of the earth.

Most tours will take you 4 km (2.5 miles) along the river. Some tours with special permits organised in advance can explore all 8.2 kilometres (5 miles). That far into the cave, boats can no longer pass and visitors have to swim between the rock walls.

Conquer your fears of small, dark spaces however, and you’ll be treated to the rare sights of waterfalls gushing through the cave walls, a unique 20 million-year-old fossil of a sirenia or manatee, and a tiny rock passage that leads into a vast room, carpeted from floor to ceiling in glimmering crystals.

Even the journey to the cave itself is worth it: you’ll enjoy a scenic 20-minute boat ride across the sea, past towering limestone karsts and walk through the national park, home to monkeys swinging through the tree canopies and giant monitor lizards slinking their way through the undergrowth.

How to get to Puerto Princesa underground river

The jumping-off point for the underground river is the small village of Sabang. Sabang is located around 40km (24 miles) north of the capital of the island – also called Puerto Princesa. You can book a day tour from the capital or stay in Sabang itself. Along with a lovely beach, it has a couple of luxury resorts and affordable beach huts.

In order to protect the river ecosystem, all visitors must have a permit. While you can organise permits and boat hire yourself, joining a tour is much simpler. Due to limited capacity and high demand, it’s best to book at least a few days in advance.

What to expect on your visit

Tours from Puerto Princesa usually include transport and permits and often lunch. From Sabang, tours are shorter (and cheaper) but you may have to arrange a permit separately. You can get one at the office on the wharf.

Helmets and life jackets are provided and must be worn for the duration of the tour (which lasts around 45 minutes). Remember to keep your mouth closed when you look up, as the cave is also home to thousands of bats, who often drop unwanted "gifts" (read, faeces) from above.

An audio guide is available on most tours and provides lots of scientific information about the river and the caves (as well as atmospheric music). If you find yourself looking around in bewilderment trying to spot the different formations, remember you can remove your earphones and let your imagination take over.

Top image: Entrance of Puerto Princesa Palawan subterranean underground river © VIew Apart/Shutterstock