In addition to the main island of Palawan Island, the ecoregion includes Balabac Island to the south, Ursula Island, and the Calamian Islands to the north. Palawan Island is 260 km long and averages only 25-30 km wide. A mountain range runs up the middle of the island, with almost half of the slopes averaging over 30 degrees. The highest point is at Mount Mantalingajan. The islands are relatively young, having been lifted up from the sea only 5-10 million years ago.