Which cave in the Philippines is home to a UNESCO-listed underground river?

The Philippine cave home to a UNESCO-listed underground river is the Puerto Princesa Subterranean River.

The river runs through a limestone karst cave system in Puerto Princesa Subterranean River National Park on Palawan's western coast. It flows underground for about 8.2 kilometers before reaching the South China Sea, and visitors commonly explore the navigable portion by boat from the coastal village of Sabang. Seawater extends into the cave, creating an underground estuary where freshwater and saltwater mix.

UNESCO inscribed the national park as a World Heritage Site in 1999 because it combines an exceptional cave-and-river landscape with a mountain-to-sea ecosystem and important biodiversity. The park includes large chambers, stalactites, stalagmites, bats, swiftlets, and other wildlife. One chamber, known as Italian's Chamber, is especially large.

The site is also widely called the Puerto Princesa Underground River. That shorter name can cause confusion, but both names refer to the same celebrated natural feature. The river was once described as the world's longest underground river, but a longer underground river discovered in Mexico in 2007 ended that claim.