The island of Palawan is an elongated stretch of thickly forested landscape bordered by coves, beaches, lagoons and limestone cliffs, stretching from southwest of Luzon towards Malaysia. The island's Tubbataha Reef is extremely ecologically important to the Philippines as a feeding ground and nursery for marine life, and the area is archaeologically important too. Caveman remains have been discovered on the island dating back 22,000 years. The main attraction on the island, however, is the underground river, St Paul's Subterranean Cave near Sabang, about two hours by road from Puerto Princesa. The cave extends more than five miles (8km) and contains the world's longest underground river. Palawan is still 'off the beaten track', but it can be reached by a flight from Manila.