Lake Superior is the second largest lake in the world next to the Caspian Sea, and has more surface area than any other freshwater lake. Its surface area (82,367 km2) is larger than the State of Maine. The lake was formed approximately 14,000 years ago by the retreat of continental ice-sheet together with the other Great Lakes. It is surrounded by hills and cliffs which offer the most spectacular landscape of any of the Great Lakes. The largest island, Isle Royale, is a United States National Park.

The Apostle Islands of Wisconsin are now a National Lakeshore, with beautiful scenery and geological features. The long, hooked arm of the beautiful Keweenaw Peninsula is also a National Lakeshore of Michigan. The lake water flows out to L. Huron through the St. Mary's River from the eastern end.

There are no large cities along the Canadian northern shore of this lake except for Thunder Bay, Ontario. Twin cities, Duluth and Superior, are situated at the western end of the lake. A large amount of ore and grain is loaded for transport abroad in the harbors of these cities. The 1,900 km journey from Duluth, Minnesota, to Kingston, Ontario, is the longest inland water transportation route in the world. The lake water is still oligotrophic and transparency at the centre of the lake is generally around 9m.