Michigan, Lake, lake in north central United States, third largest of the Great Lakes, and the only one lying wholly within the United States, bordered by Michigan on the north and east, Indiana on the south, and Illinois and Wisconsin on the west. The lake is 492 km (306 mi) long and up to 190 km (118 mi) wide, with an area of 57,757 sq km (22,300 sq mi). The maximum depth is about 281 m (about 922 ft), and the surface is 176 m (577 ft) above sea level.
The northern outlet for Lake Michigan is the Straits of Mackinac, which connect it with Lake Huron. The Chicago Sanitary and Ship Canal connects the lake to the Mississippi River. Green Bay on the western shore and Grand Traverse Bay on the eastern shore are the main indentations. The lake has a complex system of lighthouses, buoys, weather report and storm signal stations, and other navigational aids maintained by the federal government. The northern portion of the lake, which is blocked by ice for about four months a year, is the site of several islands; Beaver (about 80 km/50 mi long), Garden, and North and South Manitou islands are the largest. Chicago, Milwaukee, and Muskegon are all on the lake. Restocking of lake trout and introduction of coho salmon have revived sport and commercial fishing in the lake. The first European to describe Lake Michigan was the French explorer Jean Nicolet in 1634.