La Trinité-sur-Mer is a commune in the Morbihan department in Brittany, in north-western France. Inhabitants of La Trinité-sur-Mer are called Tri…La Trinité-sur-Mer is a commune in the Morbihan department in Brittany, in north-western France. Inhabitants of La Trinité-sur-Mer are called Trinitains. 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.