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.
Esla (river) The Esla is a river in the provinces of León and Zamora in the northwest of Spain. It is a tributary of the Duero River that starts in the Cantabrian Mountains and is 275 km long. Its direction of flow is from north to south. It is the largest tributary of the Duero in terms of discharge; in fact, at its mouth at the confluence with the Duero, it has a greater discharge than the volume in the main river.