The river of the swallows, Palawan

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An extraordinary underground estuary that flows into the South China Sea, on the western coast of Palawan, after a subterranean journey of almost 8 kms.

A national park since 1971, the St. Paul area was declared a Unesco World Heritage in 1998. In 2011, 40 years after the park’s foundation, the cave that crosses the mountain has been awarded among the New Seven Wonders of Nature. The reason why this area is considered an exceptional site is simple: it gathers a unique series of features that span from geology to biology, from surface and deep karst environment to underground climate, from mineralogy to morphology. The St. Paul mountain reaches only 1028 m in altitude, but contains what is considered a true wonder of our planet: the Puerto Princesa Underground River, that after a subterranean journey of over 6 km flows out into the South China Sea. The river is therefore subject to the tides, that reach up to 4.5 km inside the mountain. The river and the sea contribute to create one amongst the richest tropic chains in the world: bats, swallows, spiders, snakes, centipedes, amplipigia, scorpions, crabs and fish are the still partially unknown inhabitants of a unique ecosystem. The outer surface of the mountain is mostly karstic, that is composed of limestone shaped in deep grooves and sharp blades, making it one of the least inaccessible territories of the planet. The coastline offers hundreds of bays, reachable only by boat or on foot through deep forests.

Related projects

La Venta – Palawan


Puerto Princesa – Underground River

Logistics and transports
  • tent
  • boat
  • jeep

Points of interest

  • Puerto Princesa Underground River
  • Mt. St. Paul
  • The Daylight Hole
  • The relict giant caves (Tagusan, Horror, Layag, Million Bird, Memory)
  • The seashore and the St Paul Bay
  • Little Underground River


The fishermen' village of Sabang, centre of the protected area, is easily reachable from the City of Puerto Princesa, capital of Palawan. The entrance of the cave may be reached either by boat or on foot. The underground river may be navigated on paddle boats for almost 5 kms. Walking on the surface of the mountain, instead, represents a real challenge, and any kind of activity on surface requires deep knowledge and skills.