Located on the island province of Palawan in the Philippines, Puerto-Princesa Subterranean River National Park features limestone rock formations and an underground river that empties into the sea. The rock formations, comprising about 90% of the park, include pinnacles, shafts and dolines (sinkholes). The subterranean river, the Cabayugan, travels under Mt. St. Paul and empties into St. Paul's Bay, flowing underground for most of its length. Tourists interested in seeing the underground river can take a 45-minute guided tour led by park officials.
Rolex Dela Pena / EPA
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