Tham Sa-kern National Park is situated in an approximate area of 155,200 rai, covering the areas of Pa Nam-yao and Pa Nam-suad National Conserved Forest in Song-kwae District of Nan Province, and being the source of streams and basins in the Class of 1(a). The National Park has many beautiful sightseeing spots.

The geographical features of the National Park consist of high mountains, extending northwards in the shape of T. The altitude of the National Park is approximately 300-1,752 meters above the medium sea level. Doi-Ji is the highest mountaintop (1,752 meters above the medium sea level). The National Park is the source of 3 basins including Upper Yom River Basin, Upper Yao River Basin, and Lao Basin, which are the sources of main rivers of the country, i.e., Yom River and Nan River, being used for agricultural activities of villagers on both sides of the rivers.