Mainly the territory of the national Park Thung Salaeng Luang, an area of 1262 sq km, consists of limestone hills with a height of from 300 to 1028 meters above sea level. However here happen to be plain. Through the Park flows the river Vang Thong. Most of the hills are covered with deciduous and mixed deciduous forests, rarely tropical evergreens and meadows.

The proposal to include Thung Salaeng Luang in the list of national parks of Thailand arrived in 1959, has performed it in 1972. Since the late 50's to early 70's forest Park was used as the main locations of the guerrillas of the Communist party of Thailand.

The national Park is amazingly beautiful three-tiered waterfall of Kaeng song (or Namtok Kaeng Sopha). It is the largest in Phitsanulok province for which he will receive the nickname “Niagara” by analogy with the largest waterfall in the world. In June 2007 the image of Kaeng Sopha was released a postage stamp in a series of “Waterfalls of Thailand”.

Fauna of the national Park is rich and diverse. It is home to elephant, palm civet, yellow marten and more than 160 species of birds. The most valuable of them is the rare Siamese pheasant.

Especially Thung Salaeng Luang beautiful from November to December, during this period of bloom of wild meadow flowers, which in turn attract local fauna. The most beautiful and popular place at this time is plain Thung Non Sleep.