The Vilaine is a river in Brittany, in the west of France. The river's source is in the Mayenne département (53), and flows out in the Atlantic Ocean at Pénestin in the Morbihan département (56). It is 218 km long. The river is joined to the Ille and the Rance by means of the Canal d'Ille-et-Rance by the commune of Rennes.