The National Park Puerto Princesa Subterranean River is a national park which is located about 50 km north of the city of Puerto Princesa in the province of Palawan in the Philippines. It is located in the mountains of St. Paul, on the north coast of the island. Since 1992 the park is administered by the city of Puerto Princesa.
In the park there is a landscape karst, limestone, with an underground river navigable for 4.5 km of its length. This river flows through a cave before flowing directly into the South China Sea. In the cave there are many stalactites and stalagmites, as well as some large rooms. The end of the river, which is believed to be the second-longest underground river in the world, is subject to tides.
