From the World Heritage inscription:
This park features a spectacular limestone karst landscape with an underground river. One of the river’s distinguishing features is that it emerges directly into the sea, and its lower portion is subject to tidal influences. The area also represents a significant habitat for biodiversity conservation. The site contains a full ‘mountain-to-sea’ ecosystem and has some of the most important forests in Asia.
First, I should note that the mayor of Puerto Princessa is Edward S. Hagedorn.
The underground river is really pretty cool. The river goes into the mountain about 6km, but the tours only go in about 1km. The inside of the cave has tons of stalactite and stalagmite formations, most of which are named after things they look like, which usually requires a lot of imagination. Outside the cave, I saw huge monitor lizards and macaque monkeys. The underground river on Palawan is the longest navigable underground river in the world.
View my complete list of UNESCO World Heritage sites.

Hi! I live in the Philippines but sadly i haven’t step foot on Palawan. you are so lucky to have been there :D good luck on your future travels
pls.continue supporting and give your votes to puerto princessa under ground river!!we are currently number 1. dont let the rival take the lead.caution its amazon river..go philippines
Definitely on my list to go the next time Im in the PI.