Lake Superior is the largest freshwater lake in the world by surface area and world's third-largest freshwater lake by volume [Only Lake Baikal in Siberia and Lake Tanganyika in East Africa contain a greater volume of fresh water].
Lake Superior, on the United States/Canada border is the freshwater lake. Lake Superior covers 31,700 square miles which is greater than the combined areas of Massachusetts, Vermont, Rhode Island, Connecticut, and New Hampshire. Lake Superior is the deepest of the Great Lakes. Along much of Minnesota's North Shore, the lake is 700 feet deep (213 meters) within 3 miles (4.8 kilometers) of land. [Source: http://www.seagrant.umn.edu/superior/facts]. It has a maximum length of 350 miles (563 km) and maximum breadth of 160 miles (257 km). Lake Superior contains 2,900 cubic miles of water.
Lake Superior have recorded waves of over 40 feet in height. Over 300 rivers and streams empty into Lake Superior. According to a study by professors at the University of Minnesota Duluth, Lake Superior warmed faster than its surrounding climate [Source: http://www.newscientist.com/article/mg19426064.100]. Although 39 °F (4 °C) is almost a constant temperature below 110 fathoms (660 ft; 200 m) but the temperature of the surface of Lake Superior varies seasonally. The lake is seasonally stratigraphic because of this variation. The lake water thoroughly mix twice a year when the water column reaches a uniform temperature of 39 °F (4 °C) from top to bottom. This feature makes the lake dimictic.
Lake Superior has a retention time of 191 years because of its volume. If straightened out, the Lake Superior shoreline could connect Duluth and the Bahama Islands. The lake is fed by over 200 rivers including the Pic River, the St. Louis River, the Pigeon River, the Nipigon River, the White River, the Michipicoten River, the Bois Brule River and the Kaministiquia River. The southern shore of Lake Superior between Grand Marais, Michigan, and Whitefish Point, according to shipwreck historian Frederick Stonehouse, is known as the "Graveyard of the Great Lakes". More ships have been lost around the Whitefish Point area than any other part of Lake Superior.
The largest island in Lake Superior is Isle Royale in the state of Michigan. Isle Royale contains several lakes, some of which also contain islands. Other large famous islands include Madeline Island in the state of Wisconsin and Michipicoten Island in the province of Ontario.