Doi Soi Malai Petrified Wood National Park

Doi Soi Malai-Petrified Wood National Park, in Tak Ok subdistrict of Ban Tak district, protects the world’s longest fossilised tree trunk: a 69.70-metre log of ancient Koompassia malaccensis wood, dated to roughly 120,000 years old and certified by Guinness World Records in 2022. Entry is free. The site is still officially “in preparation” (เตรียมการ) toward full national park status, managed alongside the neighbouring Mae Tuen Wildlife Sanctuary.

Seven excavation pits are open along a marked walking route, each holding petrified wood fragments ranging from a few centimetres to several metres long. Pit 1 — known locally as “the valley of the giant tree” — holds the record log itself: unearthed in 2003 at 72.22 metres, it lost more than two metres off its tip to flood damage before its final Guinness measurement. The fossilisation happened when silica-rich groundwater slowly replaced the original wood tissue over millennia, preserving even the bark texture in stone. Paths between the pits are flat and shaded by cold-climate pine forest, easy walking for most fitness levels.

Doi Soi Malai’s summit — a separate hike with its own attraction page — rises above the park at around 1,600 metres, looking down over the Bhumibol Dam reservoir. During the rainy-season breeding period, the forest floor here is one of the few places to spot กะท่าง (Tylototriton), Thailand’s only salamander species: a pink-bodied, endangered newt whose males flash bright orange markings when breeding. Sightings are a matter of luck, not a guaranteed feature of a visit.

The petrified wood pits are open daily 08:00–17:30 with no admission charge. November to January brings the clearest skies and coolest temperatures for walking the pits and any onward hike. The summit and Doi Soi Dao trekking routes run on a separate seasonal opening window — roughly December through June — so check with the park office (0 2562 0760) before planning anything beyond the wood pits. Simple guesthouses, tents, and camping space are available on site, and Ban Tak district’s small town centre — the nearest base with shops and food beyond the park gate — sits within easy reach of Tak province’s other sights.

Insider Tip: Go to Pit 1 first — it’s the only pit with the full-length record log, and the morning light before 10am makes the silica-streaked stone easier to photograph than the midday glare.

Watch out: The petrified wood site and the Doi Soi Malai summit are two different hikes with two different access rules — don’t assume a ticket or opening time for one covers the other.