Lake Superior is the northwestern most and the largest of the five Great Lakes in North America and one of the world’s largest drinking water. Restricted to the east and north with Ontario (Canada), to the west of Minnesota (USA), and to the south with Michigan and Wisconsin (USA), they emptied into Huron Lake at its eastern end across the River St. Mary. The lake is 563km long (east-west), and its largest width is 258km from north to south. It has a height of 180m above the sea level and a maximum depth of 406m. The lake is 127.700 km2, only its surface area is 82.100 km2. Due to its large size (relative to the catchment area), and the porosity of the dam at its exit, long-term changes in the lake level are significantly lower than in any of the other lakes generally less than 1m. A large part of the coastal area is poorly populated. In winter, the temperature around the lake rarely drops below minus 34 ° C. June and July are peaceful months, while October and November are prone to storms. During most of the winter, the lake is 40 to 95 percent covered with ice, although it is rarely completely frozen.