Tham means cave and the Tham Pha Phueng is said to be the deepest cave of Thailand, a bit difficult to find as there are no signs and the entrance is not really taken care off. A cave with a very impressive entrance, about 20 meters wide for 20 meters high, at the base of a rock more than 50 meters high. A stream accompanies you inside the cave, then falls into the subsoil. In the cave, after a 25 meters downhill, you can walk inside for about 300 meters, with caution. In the area are many other caves, like Tham Phu Hua Lan, Tham Ho Ying, Tham Ho Chai, Tham Champi, Tham Pha Daeng, Tham Nam Dan. For more information about Nan province have a look at Destination Travel Guide Nan.