The Puerto Princesa Underground River is reputed to be the longest navigable underground river in the World. It is one of the few such rivers which the public can easily experience and appreciate. It is the official entry of the Philippines and is 1 of the 28 finalists to the Search for the New 7 Wonders of Nature.

It is a source of pride and a key element in the identity of the people of Puerto Princesa in particular, and of the Philippines as a whole.