Nam Phut Thap Lao

Nam Phut Thap Lao is a natural spring in Chaiyaphum’s Khon San district, not a waterfall — the name literally means “spring water of Thap Lao,” and groundwater pushes up through a limestone aquifer into a broad, glass-clear pool inside a 160-rai (25.6-hectare) forest arboretum. The Royal Forest Department established the site in September 1993 as a botanical reserve and picnic ground, and it remains one of the few places in this part of Isan where you can swim in cold, spring-fed water shaded by mixed forest.

The main pool sits where the spring surfaces, deep enough for a proper swim and clear enough to see straight to the sandy bottom. From there the water spreads into a shallower, winding stream over sand and gravel, breaking into smaller pools that suit families better than the deeper main basin. The water carries no odor or taste, stays noticeably cooler than the surrounding air, and flows continuously through the year — it isn’t dependent on rain the way the region’s seasonal waterfalls are. Tall trees ring the pools, keeping much of the site shaded even at midday, and small food stalls set up along the bank selling som tam and grilled chicken to visitors cooling off in the water.

The atmosphere here is unhurried: locals treat it as a swimming hole and picnic spot rather than a sightseeing stop, so weekday visits can mean having a pool largely to yourself. A basic camping area and a walking trail loop through the arboretum’s tree collection, useful if you want to stay past a single afternoon. Insider Tip: the spring occasionally turns cloudy after unusually heavy regional rain, or even distant seismic activity — in 2025 a Myanmar earthquake briefly stirred sediment here, and it cleared within days, so don’t be put off by a murky report from a few days earlier.

Bring swimwear, a towel, and cash for the food stalls, since there’s no ATM nearby. Wear sandals you don’t mind getting wet on the walk from the car park, and pack out any rubbish — there’s no collection service at the pools. Two other Khon San district sites worth combining with a visit are Chulabhorn Dam, a short drive away, and Phu Khiao Wildlife Reserve for those with more time in the district.