This is the entrance to the world's longest underground river, the Puerto Princesa Subterranean River National Park. It lies in under a mountainous landscape abundant in limestone, and flows directly into the South China Sea.

For a Cave to be nominated in the World Wonders, a cave such as this includes major stalactites and stalagmites formations and several large chambers.

Shown here is the mouth of the cave, a clear breath-taking lagoon shaded by trees that adds to the relaxing coolness of the place.