The world’s longest underground river: an 8-kilometer dark cave holds a “natural condom”

Reporter Chen Ziying / Reported from the Philippines

The rise in popularity of Palawan in the Philippines comes from its title as the “best island in the world,” but this place is even more astonishing than travelers imagine. A winding river hidden deep in the mountains, stretching 8 kilometers, is the “world’s longest underground river” and has been designated a UNESCO World Natural Heritage Site, as well as one of the New7Wonders of Nature;As visitors drift deeper into the mountain rivers on wooden rafts like characters in a wilderness reality show, they even discover a massive natural “condom”?


▲ The “world’s longest underground river” in the Philippines is pitch black without a flashlight. (Photo / Reporter Chen Ziying)

The Puerto Princesa Underground River Park is located on the western coast of central Palawan,Senior guide Arjun said that the 8-kilometer-long river in the mountains was discovered by locals in 1887, but no one dared to explore it because they believed such a mysterious river full of bats must be haunted by evil spirits. So they asked foreigners to go in instead. “Once you get inside the boat, it’s unbelievable—those winding river bends seem to have no end.”Due to the river’s length and safety concerns, visitors can only travel about 1.5 kilometers, and those who wish to go further must apply to the government. Paddling to the end takes around 4 hours, making it currently the longest discovered underground river in the world.


▲ The underground river is located on the western coast of Puerto Princesa. (Photo / Reporter Chen Ziying)


▲ The underground river was discovered by Filipinos back then, but rumors of evil spirits kept people from entering. (Photo / Reporter Chen Ziying)

▲ Ever since being listed as a UNESCO World Natural Heritage Site, it has attracted visitors from all over. (Photo / Reporter Chen Ziying)

“Please look to your right—you’ll see the biggest natural condom!”What’s astonishing about the underground river isn’t just its length. Along the 10-meter-high cave walls, bizarre stalactites spark the imagination. One formation, several meters tall, is jokingly referred to by locals as a condom. Along the way, guides also point out giant jellyfish, tulips, dinosaur heads, and more, while encouraging passengers to use their own creativity.

Before entering the underground river, it’s essential to wear a life jacket, but even more important is to put on a helmet. You might think it’s to protect against falling rocks, but that’s not the case. Guide Arjun explains:“There are just so many bats and swiftlets inside the cave. The helmet is actually to guard against falling droppings. And most importantly, never look up while talking—because poop might just land right in your mouth...”


▲ A “huge condom” spotted inside the underground river.



▲ % The imaginative shapes formed by stalactites under the beam of the flashlight amaze everyone.

Postscript: Since there is no lighting inside the cave, only the handheld flashlights of the crew are available. Travelers who want to take photos can ask the crew to fix the flashlight on a certain spot—it will help capture better images.

Introduction to Palawan Island
A long, narrow island located in the southwestern part of the Philippines, administratively part of Palawan Province. Most areas remain undeveloped and are rich in biodiversity. Covering an area of approximately 11,785 square kilometers, it is the fifth-largest island in the Philippines.Travelers from Taiwan can fly with Cebu Pacific to Manila and then transfer to Puerto Princesa International Airport to reach the Puerto Princesa area, or choose Philippine Airlines, which began offering direct chartered flights to Puerto Princesa after February 13, 2015.