Elsewhere in this 550-sq-km park, Tham Phra That is a cave with a variety of limestone formations. Guides carrying paraffin lamps lead visitors through the gloom, pointing out the translucent rocks, glittering crystals and bat-covered caverns. Geologists find the caves of interest due to a clearly visible fault line. You will need your own transport or a guide to reach the cave, which is 12km northwest of the park entrance, or you can negotiate a ride with park staff. The approach road is a dirt track and there is a stiff walk up to the cave entrance. Another 5km north is the enormous and scenic Si Nakharin Reservoir.