Thung Salaeng Luang National Park is a national park located in the Phitsanulok and Phetchabun Provinces of Thailand. It encompasses substantial portions of Amphoe Wang Thong and Amphoe Lom Sak.
The park consists of limestone hills, slate and hardpan at altitudes ranging from 300 to 1,028 meters. Thung Salaeng Luang is inlaid with meadows, especially in the southern portions of the park. The park is also the source of numerous streams. There are large salt licks at Pong Sai in the north-west and Pong Thung Phaya in the south-west. the Wang Thong River flows through the park.
The park's forest is primarily classified as deciduous, with lowland scrub and tropical broadleaved evergreen covering smaller areas.
The average annual temperature is 25°C, although temperatures often reach 30°C during late spring and early summer. The average annual rainfall is 1.7 meters.
Thung Salaeng Luang was proposed for inclusion in the national parks system In 1959. Thung Salaeng Luang was declared a national park in 1972. From the late 1960s to the early 1980s, the park's forest was used as a major base for guerrillas of the Communist Party of Thailand.
Thung Salaeng Luang National Park is home to the Kaeng Song Waterfall, (or Namtok Kaeng Sopha) which is a three-tiered waterfall of the Wang Thong River. Shaped like a stairway, Kaeng Sopha is the largest waterfall in Phitsanulok, and it has been dubbed the Niagara Falls of Thailand. The torrents are very strong in the rainy season. The vapor rising in the area creates a vast rain-like curtain. Kaeng Sopha is the subject of a June, 2007 postage stamp in Thailand in the Thailand Waterfall series.
