Subterranean River, the Navigable Underground River

Located in the city of Puerto Princesa, Palawan in the Philippines, the Puerto Princesa Subterranean River National Park is a limestone karst mountain landscape with an 8.2 kilometers navigable underground river. This park is included in the UNESCO World Heritage List.

Subterranean River entrance (Source)

The underground river is said to be the world's longest. At the mouth of the cave, a clear lagoon is framed by ancient trees growing right to the water's edge. Monkeys, large monitor lizards, and squirrels find their niche on the beach near the cave.

Inside the Subterranean River (Source)

Inside the Subterranean River (Source)

Inside the cave are major formations of stalactites and stalagmites, and several large chambers.

Subterranean River rock formation (Source)

Subterranean River rock formation (Source)

Subterranean River rock formation (Source)

The most spectacular feature of the river is that it winds through a cave before flowing directly into the South China Sea. The lower portion of the river is subject to tidal influences.

Subterranean River exit (Source)