Which Thai festival of lights involves floating lanterns on water?

The Thai festival of lights that involves floating lanterns on water is Loy Krathong.

During Loy Krathong, people place small decorated vessels called krathongs on rivers, canals, ponds, or lakes. Traditional krathongs may be made from banana-trunk sections and banana leaves, and commonly carry a candle and incense. Participants often make a wish or symbolically let go of anger, misfortune, and past troubles as the float drifts away.

The festival takes place on the full moon of the 12th month in the traditional Thai lunar calendar, usually in November. Its name combines loi, meaning “to float,” with krathong, a small floating vessel. Loy Krathong is often confused with Yi Peng because both are celebrated around the same time in northern Thailand. The distinction is useful: Loy Krathong centers on waterborne floats, while Yi Peng is especially associated with lanterns released into the sky.