Chiang Saen Lake () is a natural freshwater lake in Thailand, it is located in Yonok Subdistrict, Chiang Saen District, Chiang Rai Province, northern Thailand.
According to the folklore, the legend of Singhanavati (ตำนานสิงหนวัติ), it used to be an ancient kingdom known as Singhanavati or Yonok. The kingdom was destroyed by a sudden flood from earthquake in 545. The town was submerged and is known today as "Wiang Nong Lom" (เวียงหนองหล่ม, ) an archaeological swamp south of the lake.
The lake has a total area of 2,711 rais (1,071 acres, 4.342 km2). It was originally just a small swamp, until a dam was built to block the waterway overflow until a large lake was formed known as Nong Bong Kai (หนองบงคาย). In 1985 it was declared as Nong Bong Kai Non-hunting Area.
The lake is home to large flocks of migratory waterfowls from November through February. Bird species found here are lesser whistling duck, grebe, common pochard, watercock. There is a campsite for visitors. Chiang Saen Lake is the northernmost lake in Thailand.
See also List of protected areas of Thailand List of Ramsar wetlands of Thailand References