Bouches-du-Rhône is a department in southern France. It borders Vaucluse to the north, Gard to the west and Var to the east. The Med…Bouches-du-Rhône is a department in southern France. It borders Vaucluse to the north, Gard to the west and Var to the east. The Mediterranean Sea lies to the south. Its prefecture and largest city is Marseille; other important cities include Aix-en-Provence, Arles, Martigues and Aubagne.