Phu Sang National Park

Phu Sang National Park covers around 280 sq km along the Thailand-Laos border in Phayao province, roughly 90 km from Phayao town via Chiang Kham. Entry costs 100 THB for foreign adults (50 THB for children) and 20 THB for Thai adults (10 THB for children), plus a car park fee, at the gate near the park office.

The park’s signature feature is Namtok Phu Sang, a waterfall where the water itself runs warm — a rarity in Thailand, fed by the same geothermal source as the park’s separate hot spring pools nearby. The lower tiers are shallow enough to sit in, and unlike most Thai waterfalls the water doesn’t cool the air around it; if anything it’s a mild, sulphur-tinged warmth. Beyond the falls, the park holds limestone caves, forested ridges rising toward Doi Pha Mon, and stands of Burmese padauk, teak, and cigar-box cedar that support one of the last strongholds of the Siamese big-headed turtle (Pu Lu in Thai) — a long-tailed, large-headed species classed as endangered, largely due to forest fires destroying its streamside habitat.

Insider Tip: Ask at the park office about the turtles’ usual haunts before you go looking — they’re most active after dark near the clearer creeks, and staff can point you to where they’ve been spotted recently rather than you searching blind.

Watch out: The warm water at the falls draws crowds on weekends and Thai holidays, especially during the cool season (Nov-Feb) when a naturally heated pool is genuinely appealing. Visit on a weekday if you want the lower pools to yourself.

The park runs basic accommodation, camping areas, and a small convenience store near the headquarters, so it works as an overnight stop rather than just a day visit — useful if you’re combining it with Phu Chi Fa further along the border, which is close enough for a two-site loop through this corner of Phayao. By car, follow the Phayao-Chiang Kham route, turn onto Highway 1093 about 6 km past Chiang Kham, and continue roughly 17 km to the park entrance; from Chiang Rai, the Thoeng-Chiang Kham road covers the same ground from the other direction. Buses run from both Phayao and Chiang Rai to Chiang Kham, with connecting minibuses onward toward Ban Huak passing the park office.