Ardèche is a tributary of the river that has a mouth at what body of water?
Rhône The Rhône ( ; French: "Le Rhône" ] ; German: "Rhone" ] ; Walliser German: "Rotten" ; Italian: "Rodano" ] ; Arpitan: "Rôno" ] ; Occitan: "Ròse" ] ) is one of the major rivers of Europe and has twice the average discharge of the Loire (which is the longest French river), rising in the Rhône Glacier in the Swiss Alps at the far eastern end of the Swiss canton of Valais, passing through Lake Geneva and running through southeastern France. At Arles, near its mouth on the Mediterranean Sea, the river divides into two branches, known as the Great Rhône (French: "Le Grand Rhône") and the Little Rhône ("Le Petit Rhône"). The resulting delta constitutes the Camargue region.
Arc (Provence) The Arc is an 83 km long river in the south of France. It arises at an elevation of 470 m , close to the village of Pourcieux. It then passes through Aix-en-Provence before flowing into the Étang de Berre, a lagoon connected with the Mediterranean Sea to the west of Marseille. Its drainage basin, with a surface area of 727 km2 , is divided between two départments, Var and Bouches-du-Rhône. The Bayeux, the Cause and the Torse are its tributaries.