Pa Phaisali

Pa Phaisali is Nakhon Sawan’s Royal Forest Park — officially the Phaisali Centenary Arboretum, opened in 1997 to mark the Royal Forest Department’s 100th anniversary and renamed in 2015. It isn’t a national park under Thailand’s National Park Act, despite older listings using the term — it’s a forest reserve and arboretum at the edge of the wider Soi Dao mountain range, which stretches across the borders of Nakhon Sawan, Phetchabun, and Lopburi provinces.

The two waterfalls inside the reserve, Namtok Sab Samobol and Namtok Sab Yai, are the main reason to make the drive: seasonal drops that only really run from June through October, fed by the same monsoon rains that green up the mixed deciduous and dry dipterocarp forest around them. A marked trekking route connects the two falls, running 7 to 15 kilometres depending on which trailhead you start from — short enough for a half-day hike, long enough that some visitors split it into an overnight camp instead.

Insider Tip: Soi Dao’s summit, inside the reserve, is a genuine sunrise-and-sunset camping spot with panoramic views over the forest canopy. Bring your own tent and gear, since facilities at the top are minimal, but the payoff is one of central Thailand’s better hilltop views without the crowds of the more famous northern viewpoints.

The best window to visit runs from around July through December: the waterfalls are still flowing from the tail end of the rains, and the worst of the downpours has usually passed by October, leaving trails firm enough to walk without turning to mud. Outside that window — the dry, hot-season months of February to May — the falls run dry or near-dry, and the trek becomes a forest walk rather than a waterfall hike.

Watch out: Trail markings thin out past the main waterfall junctions, and mobile signal drops out for long stretches once you’re deep in the reserve — this isn’t a solo first-timer’s hike without a local guide or a clear map downloaded in advance.

Facilities are basic: a ranger station, a couple of short nature trails suited to casual visitors, and camping areas for those doing the longer route. There’s no public transport to the reserve — a car or motorbike from Nakhon Sawan town, roughly an hour’s drive through Phaisali district, is the only practical way in.