Phu Suan Sai National Park

Phu Suan Sai National Park, also known as Na Haeo National Park, is a protected mountainous park in Na Haeo District, Loei Province, northeastern Thailand along the Thailand-Laos border. Covering about 178 sq km, it is notable for pine forests, sandstone mountains, viewpoints and waterfalls. Established in 1994, it preserves dry evergreen and mixed deciduous forests and offers camping, trekking and border scenery.

Visitors can expect a forested mountain landscape on the Thai-Laos border with pine-covered hills, sandstone cliffs and viewpoints such as Phu Hua Hom. The park has a visitor centre, marked nature trails, waterfalls including Tat Hueang Waterfall on the border, camping grounds and bungalows. Areas to explore include viewpoints for sea of mist, forest trails and the border waterfall area. The environment is quiet and natural with cool temperatures in winter.

Originally established as Na Haeo National Park and later renamed Phu Suan Sai National Park, it was declared Thailand's 79th national park in 1994 to protect border forests, watersheds and pine and dry evergreen forests in Na Haeo District. The park covers approximately 178.84 sq km along the Thailand-Laos border.

The park lies in a border area inhabited by Thai-Lao communities and is valued for its natural heritage, pine forests and border waterfall that is shared with Laos. It serves as a recreational and educational site for nature appreciation and local community-based tourism in Loei Province.