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 Winnipeg algae threat the 10th largest freshwater lake in the world. The lake consists of three well-defined regions, the larger North Basin, the smaller South Basin, and the connecting body of water defined as the "Narrows", all of which are greatly affected by algae blooms. The surrounding watershed drainage basin is roughly forty times larger than the lake’s surface area, this ratio is higher than any other major lake in the world; this makes Lake Winnipeg susceptible to excessive nutrient levels. Because Lake Winnipeg holds a considerable small volume of water, the water quality is determined by manmade structures and high nutrient loading.