The "Palawan 2008" expedition, in the karst of St. Paul (Palawan, Philippines), was held from February 22 to March 12, 2008. The expedition was attended by 12 Italian cavers, two Mexicans and two English. The mission was part of a larger project of research and documentation, that La Venta Association is developing in collaboration with the authorities of the Puerto Princesa Subterranean River National Park and the capital of Puerto Princesa.
Aims of the expedition were: the completion of the photographic documentation of the underground river, especially about his extraordinary biological aspect, the exploration of some cavities in the NE sector of the massif seen during the expedition in 2007, the approach to the summit areas of St. Paul entering the karst area by SO and the completion of the exploration and survey of some cavities of the S area , in the village of Cabayugan. The expedition operated simultaneously in the three areas, unfortunately in conditions made difficult by bad weather characterized by strong afternoon thunderstorms that have made risky the exploration of the active cavity. The bad weather conditions have prevented then to reach the summit areas of the limestone ridge.
The group that has worked in the NE sector has completed the exploration of two important caves that act as sinkholes as well as many blind valleys that border the eastern edge of the karst. The two caves, called Nagbituka 1 and Nagbituka 2, develop along the contact between limestone and impermeable rocks and are characterized by short pits and long slides that are crossed climbing. The explorations have allowed us to ascertain that the two caves are parallel to the main systems of the Underground River, which runs from SW to NE along the ridge of St. Paul, and probably feeds the springs located along the limestone coast. So they are not connected with the main collector of the Underground River.
Nagbituka 1 was found to be 270 m deep, which makes it one of the deepest caves of the Philippines, for a development of 650 m. The second has a depth of 130 m for a development of 450 m. Both the caves have large areas of collapse and lateral galleries with concretions. At the moment it doesn't seem possible to make new significant developments in either of the two cavities. In the area there are in any other way active sinkholes yet to be explored.
In the south sector, the one in which were concentrated the efforts of the previous expedition, were not discovered any important caves. The summit area of the limestone plateau, where in the aerial photos were clearly visible large collapsed inlets, was unattainable on that side due to the presence of steep slopes of sharp limestone blades, very difficult, and very dangerous to cross. The teams, although expert have not been able to go more than a few hundred meters beyond the edge of the limestone relief, without reaching any of the entrances seen in the aerial photos. Have been discovered some rather modest cavities of contact at the base of the limestone buttresses, with limited development and closed by the alluvial deposits.
No significant new developments, however, inside o the underground river, where some branches, detected during the early stages of exploration ( 1990-1991), have been revised. Were, however, identified a number of promising windows that need specific equipment to be climbed. Inside the underground river was made a great job of photographic documentation of the hypogean fauna.