If you look up, keep your mouth closed.

That is the first and perhaps most crucial piece of advice you will get from guides at one of the world’s longest navigable subterranean rivers, a half-submerged limestone cave located in a national park on the remote island of Palawan in the Philippines.

The reason for the warning? The 5-mile-long underground river is filled with high chambers and hanging rock formations that guides say resemble giant fruit, animals and human nudes. The cave is also home to thousands of bats that cling to its dark ceiling.

And where there are thousands of bats, there is plenty of falling guano.

But the underground river and surrounding coastal land, which make up the country’s Puerto Princesa Subterranean River National Park, is worth braving drops of bat poop.

With its towering limestone cliffs, virgin tropical forests and turquoise waters, the 14,000-acre park is among the most diverse and pristine environments in the region. It has been recognized by the World Wildlife Fund and was named a World Heritage site in 1999 by the United Nations, which deemed it one of the most impressive cave systems on the planet.

The underground river remains the star attraction. Visitors don hard hats and board canoes to enter the dark, jagged mouth, which yawns over an emerald green ocean lagoon.

At dusk, various species of large and small bats, as well as swallows, flood out over the lagoon to feed, according to guides.

Inside, spotlights on the bow of the canoes illuminate limestone formations, high ceilings — often streaked with bat guano — and vast chambers as visitors glide quietly along the glassy river. Unfortunately, only a fraction of the river is open to the general public, and deeper journeys require a special permit.

Meanwhile, the land outside the cave teems with wildlife. The park includes protected swamps, mangroves, evergreen forests and mountain jungle that provide habitat for hundreds of species including long-tailed macaques, stink badgers, monitor lizards, flying squirrels and reticulated pythons.

Such habitat is usually not very accessible and visitors must be willing to do some traveling, though nothing too rugged or grueling.

The underground river park is located far from the bustling Philippine capital of Manila and requires flying to the sparsely populated province of Palawan, about two hours to the southwest, straddling the South China and Sulu seas.

All visitors are required to buy a permit in advance to enter the park. The underground river is one of the busiest attractions in Palawan, according to local tourism officials, and it is a good idea to buy permits well in advance of a planned visit.

From the noisy port town of Puerto Princesa, the park is accessible via a winding, motion sickness-inducing, two-hour drive through the hills of Palawan.

The drive itself provides some sightseeing. There are plenty of views of coastal forests, mangroves and limestone cliffs as well as opportunities to see how rural Filipinos live.

In areas outside Puerto Princesa, many live in one-room thatched palm huts set on stilts, and dogs sleep lazily on the road. Deeper in the forest some native tribes still follow a primitive lifestyle and wear little more than loincloths.

The drive ends at the ferry port in Sabang where visitors must make a 15-minute boat ride to the park. The small town thrives on the park’s tourism and offers some places to eat and drink. The underground river is designated as a Philippine national park but is still managed by the local community, making it a unique model for environmental protection in the country.

Those who arrive at dawn can watch local fishermen bring in the morning catch of squid and fish from the South China Sea and watch the ferry boat operators prep for the daily rush of tourists.


Hotels and tourism booths throughout Puerto Princesa, Palawan’s central town, offer tours and transportation to the underground river for about $35. Hiring a private driver is also an option if tour trips are full and will cost about $100. The trip takes about two hours by vehicle.


A tour package will cost about $35, but visitors will also need to pay about $17 for the ferry ride to the remote cave entrance.


The park is open year-round but only allows a limited number of visits each day, so advance reservations are a good idea. It is often difficult to book next-day visits. Check which days are already filled up at the park website,


There are some restaurants and food stalls around the ferry port.


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