Brière (Breton: Ar Briwer) is the marsh area to the north of the Loire estuary in France at its mouth on the Atlantic Ocean. The residents of Brière are called Brièrons. The Brière marsh area includes a vast area of humid zones stretching from the Gulf of Morbihan and the estuary of the Vilaine to the north, to the salt marshes of Guérande to the west to the estuary of the Loire River and the Lac de Grand-Lieu in the south.