Lake Superior the Soo Locks. Lake Superior is the largest freshwater lake in the world in area (if Lakes Michigan and Huron are taken separately; "see Lake Michigan–Huron"), and the third largest in volume, behind Lake Baikal in Siberia and Lake Tanganyika in East Africa. The Caspian Sea, while larger than Lake Superior in both surface area and volume, is brackish; though presently isolated, prehistorically the Caspian has been repeatedly connected to and isolated from the Mediterranean via the Black Sea. Lake Superior has a surface area of , which is approximately the size of South Carolina or Austria. It has a
Lake Constance St. Gallen, and Schaffhausen. The Rhine flows into the lake from the south, with its original course forming the Austro-Swiss border, and has its outflow on the "Lower Lake" where — except for Schaffhausen — it forms the German-Swiss border until the city of Basel. Lake Constance is the third largest freshwater lake in Central and Western Europe in terms of surface area (and the second largest in terms of volume), after Lake Geneva and (in terms of surface area) Lake Balaton. It is long, and at its widest point, nearly wide. It covers approximately , and is above sea