Huoy Nam Nug hot spring

Huoy Nam Nug is a natural hot spring inside Namtok Pha Charoen National Park, in Tak’s Phop Phra district near the Myanmar border. The water surfaces sulfur-free at around 60°C, and the local subdistrict administrative organisation has developed it into three connected pools — promoted locally as an “onsen” — with free entry and no set closing time.

Bo Neung, right by the car park, is the pool most visitors reach first and the main soaking spot. Bo Song, just beyond it, is the smallest of the three. Bo Sam — known locally as Bo Chang, or Elephant Pool — is the largest, but it sits roughly 100 metres higher up the hillside and takes about a 2.5km walk from Bo Neung to reach, which keeps it noticeably quieter than the pools at the entrance.

Insider Tip: Make the walk up to Bo Chang if you want the springs mostly to yourself. Most day-trippers stop at Bo Neung and never make the climb, even though the top pool is the biggest of the three.

Watch out: the water runs close to 60°C at the source, so ease in gradually rather than getting straight into the hottest pool, and don’t stay in one soak too long. A cool mountain stream runs nearby if you need to cool off between soaks.

Namtok Pha Charoen National Park, which the hot spring sits inside, is built around a limestone waterfall with dozens of small tiers cascading through forest, connected by a nature trail of about 1.5km — worth combining with the hot spring if you’re making the trip out to Phop Phra district. The park has no separate entrance fee and keeps a couple of bungalows and tent sites for overnight stays, so it’s possible to turn the hot spring into an overnight trip rather than a day visit. Cool season, November to February, is the most comfortable stretch for hot-spring bathing — daytime temperatures are milder, which makes the contrast with the 60°C water more pleasant than during the hot season’s already-high heat. Phop Phra district borders Myanmar, and the drive out from Mae Sot passes through a mix of hill farmland and forest rather than the more developed route between Tak town and Sukhothai further east — it’s a genuinely rural corner of the province, with the hot spring one of the few developed stops along the way.