La Trinité-sur-Mer, is a commune in the Morbihan department in Brittany, in north-western France.
It is located east of Carnac. The town is primarily a port, with a seaside quay dotted by numerous seafood restaurants. The town is also known for its watersport competitions.
Separated from the well known commune of Carnac in 1864, several of the famous neolithic standing stones in the Carnac stones fall within its boundaries, including the dolmens of Kerdeneven and Kermarquer, and the Petit-Ménec Alignments.