Ton Sak Yai National Park

Ton Sak Yai National Park is a protected forest area in Tha Pla and Nam Pat districts of Uttaradit Province, northern Thailand. Established on 4 December 2003 as Thailand's 103rd national park, it covers about 324 sq km of mixed deciduous and teak forest. It is notable for protecting the largest teak tree in Thailand, a 47-meter tall tree with a 10-meter circumference estimated to be over 1,500 years old.

Visitors can expect a forested mountain landscape with dense teak and mixed deciduous forest, nature trails and viewpoints. The main attraction is the giant teak tree (Ton Sak Yai) accessible via a short forest walk with interpretive signs. The park offers quiet nature observation, photography, and camping areas near the park headquarters. Facilities are basic and the environment is natural and relatively undeveloped compared to larger national parks.

Declared as Thailand's 103rd national park on 4 December 2003 to protect one of the last remaining natural teak forests in northern Thailand. The park's centerpiece is the giant teak tree, estimated to be about 1,500 years old, which has been protected as a natural monument and symbol of forest conservation in Uttaradit.

The giant teak tree is highly revered locally as a natural heritage symbol and represents the historical importance of teak forestry to northern Thai culture and economy. The park reflects community and national efforts to conserve native teak forests for ecological and cultural value.