Phu Soi Dao National Park

Phu Soi Dao National Park straddles the border between Uttaradit and Phitsanulok in Nam Pat district, and its centrepiece is Lan Son — a pine-covered plateau at 1,633 metres, one of the largest highland grasslands in Thailand. Reaching it means a genuine trek: 6.5 km on foot from the waterfall trailhead along Highway 1268, taking 4-6 hours depending on fitness and weather. Entry runs 200 THB for foreign adults (100 THB for children) and 40 THB for Thai adults (20 THB for children); the park gate opens 08:00-16:30 daily, with hikers required to start the climb between 08:00 and 14:00 so rangers can track everyone off the trail before dark.

Two waterfalls anchor the lower part of the park. Phu Soi Dao Waterfall drops in five separate tiers and runs year-round. A longer walk reaches Sai Thip Waterfall, a seven-tiered cascade where each drop is roughly 5-10 metres, set in mossy, permanently damp forest that stays cooler than the trail around it. Both are accessible without the full summit trek, making them a reasonable half-day option if you don’t have time for the plateau.

The plateau itself is where Phu Soi Dao earns its reputation. Son Sam Bai — Khasya pine — covers the flat highland in a way that’s unusual for Thailand’s mostly tropical forest cover, and the open grassland turns into a wildflower field on a seasonal cycle: rainy-season blooms (roughly August-September) bring ground orchids and other wildflowers, while the cooler months bring different blooms and maple trees that turn red — a rare bit of autumn colour in a country that doesn’t usually get one. A marker near the plateau commemorates the Battle of Ban Rom Klao, fought along this stretch of the Thai-Laos border. There’s no accommodation or food service up here — everyone camping on the plateau carries in their own tent and supplies, and porter services are available if you’d rather not.

Watch out: The Lan Son plateau area closes to trekking and camping for part of each year — typically mid-January through June — to let vegetation recover and reduce wildfire risk during the dry season. The exact reopening date shifts slightly year to year, so call the park office before planning a multi-day trip outside the July-December window.

Insider Tip: A park ranger guide is compulsory for the summit trek, and it’s worth it beyond the legal requirement — the trail forks in a few places, and rangers know the safest water-refill points along the way. Book through the park office ahead of a weekend visit; guide slots fill up during the cooler months, when the plateau is busiest.

The park lies in Nam Pat district, a couple of hours’ drive from Uttaradit town. Budget for a full day if you’re only doing the waterfalls, or two days minimum if you’re camping on the plateau.