LAKE SUPERIOR IS THE coldest, deepest and largest of the Great Lakes, a group of lakes located along the border between the United States and Canada. Moreover, Lake Superior has the largest surface area of any freshwater lake, worldwide, at 31,700 square mile (82,100 square kilometer). To put its size into perspective, its waters could, according to the Great Lakes Information Network (GLIN), “fill all the other Great Lakes plus 3 additional Lake Eries.” GLIN was referring to Lake Erie, Lake Huron, Lake Michigan and Lake Ontario, a set of 4 lakes of significant size that, along with Lake Superior, comprise the original 5 Great Lakes; perhaps they were also including Lake Champlain, which was given the designation of the sixth Great Lake in 1998. Lake Superior has a volume of 2,900 cubic mile (12,100 cubic kilometer), the largest-volume lake in , and the third in volume worldwide. The average depth of Lake Superior is 483 foot (147 meter), with the deepest portion reaching 1,332 foot (406 meter). Its length is 350 mile (563 kilometer) and its breadth 160 mile (257 kilometer), with a shoreline that, including its islands, measures 2,726 mile (4,385 kilometer). This lake is 600 foot (183 meter) above sea level and has an average temperature of 40 degrees F (4 degrees C). The lake’s drainage basin, the area of land where streams and rivers drain into the lake, is 49,300 square mile (127,700 square kilometer) and is located in Michigan, Minnesota, Wisconsin, and Ontario, Canada. As the Earth warmed up, the resulting water—called meltwater—filled the holes carved out of sandstone, and the Great Lakes were formed. Lake Superior, in particular, has low levels of dissolved minerals; hard Precambrian rocks of the watershed beneath the lake are not easily dissolved.