Sam Pan Boak is a rock islet under the Mae Khong River. In the floods, it is covered by water and combining with the pressure of the whirlpool turns the rock islet into more than 3,000 shallow lakes or Sam Pan Boak. The word Boak in local dialect means shallow lake, which is the origin of the name. During the dry season, Sam Pan Boak appears like a hill in the middle of the Mae Khong River.