The Old Mine Of Ban Sa

A flooded lignite pit outside Ban Sa village, in Phayao’s Chiang Muan district, has become a blue-green viewpoint where the old mining terraces drop straight into still water. Sa sub-district administration manages the site as a photo stop, open 08:30-16:30 daily, free to enter.

Banpu Public Company Limited worked this seam commercially for years — a Department of Mineral Resources survey put the Chiang Muan basin’s lignite reserves at roughly 63.6 million tonnes. When mining wound down and the pit flooded, the exposed clay and mineral walls left the water an unusual turquoise that shifts with the light. Fossils turned up during excavation, and small educational displays now sit near the site as part of its rehabilitation into a public viewpoint.

A marked lookout above the water is where most visitors stop — the geometric cut of the old terraces against the flat, still surface below is the shot people come for. Morning light before 10 AM works best, once the haze that builds over Chiang Muan’s hills in the afternoon hasn’t set in. A short path runs along part of the rim with a few benches catching the breeze off the water. There’s no rental gear, no food stalls, and no marked swimming area on site — this is a lookout, not a lake resort, and the pit’s mining-era depth means the water turns cold and dark only a few metres from the edge.

Watch out: Don’t swim here unless you’re with locals who know the site well. It’s an unsupervised former mine pit, and depth changes sharply near the old excavation walls.

Chiang Muan is quiet even by Phayao standards, and the mine viewpoint draws a trickle of visitors rather than tour groups — expect long stretches of the rim to yourself outside weekends. Bring your own water and sun protection; the nearest shops and fuel are back in Chiang Muan town.

Insider Tip: Pair the stop with Kwan Phayao, about an hour south — the mine viewpoint is a 30-45 minute detour, not a half-day destination on its own.

More on the district and other lakes and reservoirs in the province at the Phayao destination guide, including Kwan Phayao and Rong Tiew Reservoir.