Damgan is a commune in the Morbihan department of Brittany in north-western France. Damgan is a coastal town located on the south coas…Damgan is a commune in the Morbihan department of Brittany in north-western France. Damgan is a coastal town located on the south coast of Brittany. The town is located 20 km southeast of Vannes. The river Penerf forms a natural boundary to the west. Historically Damgan belongs to Vannetais and Lower Brittany.