In 2010, a group of environmental activists and geologists discovered that this underground river had a second floor, indicating that there was a small waterfall inside the cave. They also found a cave dome measuring 300 m above the underground river. The deeper area of the underground river is almost impossible to explore because of low oxygen levels.
On 11 November 2011, the Puerto Princesa Underground River was selected as one of the New7Wonders of Nature, along with the Amazon Rainforest, Ha Long Bay, Iguazu Falls, Jeju Island, Komodo, and Table Mountain. The results of this election were officially confirmed on January 28, 2012.
This national park has a view of the limestone mountains. St. Underground River Cave Pauls are more than 24 km long, including 8.2 km part of the Cabayugan River. Wind rivers enter through the cave before flowing directly into the West Philippine Sea. The interior of the cave includes large stalactite and stalagmite formations, and several large rooms, one of which is the largest cave room in the world. Until 2007, during the discovery of underground rivers on the Yukatan Peninsula, Mexico, Puerto Princesa was known as the longest underground river in the world.
This area is also a habitat for biodiversity conservation. This site contains a complete ecosystem from the mountains to the sea and has several important forests in Asia. This park was registered as a UNESCO World Heritage Site on December 4, 1999.