Bueng Boraphet (Thai: บึงบอระเพ็ด, ) is the largest freshwater swamp and lake in central Thailand. It covers an area of 224 km² east of Nakhon Sawan, south of the Nan River close to its confluence with the Ping River.
Originally the area was covered by a large swamp, which was flooded in 1930 with the building of a dam to improve fishing.
This is the only known site for the White-eyed River Martin which used to winter there, but has not been seen since 1980, and may be extinct.
106 km² of lake have been declared as a non-hunting area in 1975. In 2000 it was also declared as a wetland of international importance by the Thai government.