Puerto Princesa Subterranean River, one of the best eco-tours in the Philippines

With thousands of islands, the Philippines always offers genuine beauty that is maintained in its authenticity. Palawan, the Philippines’ westernmost province, is a picture-perfect island like no other. It is a beautiful tropical paradise that is home to marvellous beaches and abundant biodiversity, rich in its inherent and exhibited natural value. The Puerto Princesa, the capital of Palawan, is no exception. Internationally recognized for its excellence in environmental care also as the cleanest and greenest city in the Philippines, Puerto Princesa has become one of the popular destinations for its exotic subterranean river; the Puerto Princesa Subterranean River. It is part of the Puerto Princesa National Park which was declared a protected area managed by the local government since 1992. Located in Sabang, on the north coast of Palawan Island in the far southwest of the Philippine archipelago, 81 kilometres northwest of the city of Puerto Princesa, the Park is bounded on the north by St Paul Bay and by the Babuyan River to the east. This 22,202-hectare national park area has an underground river of 8.2 kilometres long centres around the Cabayugan river. The Puerto Princesa Subterranean River was thought as the longest navigable underground river in the world until 2007 when two underground rivers and cave systems in Yucatan Peninsula Mexico were found to be linked.

The Puerto Princesa National Park comprises various landforms from flat plains and rolling hinterlands to hills and mountain peaks. The most impressive of these is the geologically young karst—natural rock formations created by dissolving limestone—mountain landscape of the St Paul Range, which is part of a series of rounded limestone peaks aligned north-south along the western coast of Palawan. More than 90% of the park is comprised of sharp karst limestone ridges around Mount St. Paul. The river begins about 2 km southwest of the mountain where the river plunges underground to flow underground for almost its entire length to its mouth.

Underground rivers like the Puerto Princesa are carved out of karst, a type of porous limestone rock. Rainwater from the Earth’s surface finds its way into tiny cracks in the rock and slowly drips down until its gravity-powered descent is stopped by a more solid layer of rock. As more water is collected, the pressure that water puts on the surrounding rock increases. Rainwater also has some level of acidity, so the water begins to carve its own path through the rock.

The river’s complex ecosystem has adapted to the underground environments over hundreds of years. All the charm of nature of the Puerto Princesa Subterranean River made UNESCO recognized it as a World Heritage Site that must be protected in 1999. Aside from being a World Heritage Site, on January 28, 2012, New Seven Wonders also officially announced this amazing underground river as one of the seven wonders of the world.

Unlike other underground rivers, the Puerto Princesa Subterranean River lies beneath the Saint Paul Mountains, and it is tidal in its lower reaches. It flows through the St Paul Underground River Cave before outflows directly to the South China Sea. In 2010 number of geologists and environmental activists discovered that this river had other streams above it as evidenced by the presence of a waterfall in a cave. The cathedral-like cave which is about 360 meters long and 80 meters high includes major formations of stalactites and stalagmites that are formed naturally from the content of calcium carbonate (calcite) from water droplets in the cave, and several large chambers up to 120 meters wide and 60 meters high. A small marine area is included within the Park’s boundary. The total length of the cave system is 24 kilometres. The entire area is a model for biodiversity where waterholes, river branches, and stunning rock formations as well as diverse ecosystems that are radically different from that of the rest of the Philippines. Connecting a range of important ecosystems from the mountain-to-the-sea, the Park covers the complete ecosystem runs beneath of limestone karst mountains making it one of the richest forest floras in Asia and is highly biodiverse with much of them being endemic or related to those of Borneo preserving relics of the period when the island was connected by a land bridge with Borneo. There are 233 animal species, including the critically endangered Philippine cockatoo (Cacatua haematuropygia) and Hawksbill turtle (Eretmochelys imbricate), as well as the endangered Green sea turtle (Chelonia mydas) and Nordmann greenshank (Tringa guttifer). There are some 15 endemic species of birds such as the Palawan peacock pheasant (Polyplectron emphanum) and the Tabon scrub fowl (Megapodius freycinet cumingii). There are also around 800 species of plants including 300 tree species make up the biota of this place. In addition to exploring the river in the cave, in this national park area you can also see views of the limestone line and ancient forest. It is also a habitat for various animal species such as giant spiders.

The area of the Subterranean River has attracted visitors since the middle of the 19th century. In 1997 there were nearly 40,000 visitors and the development of eco-tourism is being encouraged there. Bridges, trails, and boats provide access within the park and to the underground river which is easily navigable for the first 1.5 kilometres via canoe and led by a guide with a flashlight. More intrepid travellers can venture another 3 kilometres —with a special permit, that is— to see more of the impressive cave-dwelling stalagmites and stalactites up close. But after that, the subterranean river remains unnavigable and yet-to-be explored.

Although there is no bad time to visit the river, conditions are generally better in the dry season as the sea is calmer and the weather tends to be on the sunny side the majority of the time, which is from November to May. There is also less chance that the trip would be cancelled or delayed due to severe weather. The warmest months are from March to May, while its wet season is from June to October.

Because of its beauty and being a protected area, Puerto Princesa Subterranean River National Park activities require careful planning and management to ensure the natural values are not disturbed. In order to preserve the underground river, the local government limits the number of visitors who come every day. Registration and permit are required for the guests to enter the area. But, despite the conservation efforts, the Puerto Princesa Subterranean River National Park however is facing a series of significant threats to its watershed, further threatening the integrity and biodiversity of the park environmental resources and the quality of the visitor experience. These threats are being caused by activities both within the park boundaries and adjacent to the national park within the park’s watershed area. Existing threats within and around the park are often due to increasing population. As their number increases, so does their demand for resources to provide for their basic needs. Sadly, how resources are utilized critically put the ecosystems and the resources in the Puerto Princesa Subterranean River National Park under threat. Practices like illegal logging, illegal quarrying, slash and burn agriculture, conversion of forest to agricultural lands and road widening are causing serious damage to the environment.