Lake Michigan–Huron in the context of "Lake Superior"

The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Superior, Michigan, Huron, Erie, and Ontario (though hydrologically, Michigan and Huron are a single body of water, joined at the Straits of Mackinac). The Great Lakes Waterway enables modern travel and shipping by water among the lakes. The lakes connect ultimately to the Atlantic Ocean via the Saint Lawrence River as their primary drainage outflow. The lakes are also connected to the Mississippi River basin through the Illinois Waterway.

The Great Lakes are the largest group of freshwater lakes on Earth by total area and the second-largest by total volume. They contain 21% of the world's surface fresh water by volume. The total surface is 94,250 square miles (244,106 km), and the total volume (measured at the low water datum) is 5,439 cubic miles (22,671 km), slightly less than the volume of Lake Baikal (5,666 cu mi or 23,615 km, 22–23% of the world's surface fresh water). Because of their sea-like characteristics, such as rolling waves, sustained winds, strong currents, great depths, and distant horizons, the five Great Lakes have long been called inland seas. Depending on how it is measured, by surface area, either Lake Superior or Lake Michigan–Huron is the second-largest lake in the world and the largest freshwater lake. Lake Michigan is the largest lake, by surface area, that is entirely within one country, the United States.

Lake Michigan (/ˈmɪʃɪɡən/ MISH-ig-ən) is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume (1,180 cu mi; 4,900 km) and depth (923 ft; 281 m) after Lake Superior and the third-largest by surface area (22,405 sq mi; 58,030 km), after Lake Superior and Lake Huron. To the east, its basin is conjoined with that of Lake Huron through the wide and deep Straits of Mackinac, giving it the same surface elevation as its eastern counterpart; hydrologically, the two bodies are a single lake that is, by area, the largest freshwater lake in the world.

Lake Michigan is the only Great Lake located fully in the United States; the other four are shared between the U.S. and Canada. It is the world's largest lake, by area, located fully in one country, and is shared, from west to east, by the U.S. states of Wisconsin, Illinois, Indiana, and Michigan. Ports along its shores include Chicago, Illinois, Gary, Indiana, Milwaukee and Green Bay, Wisconsin, and Muskegon, Michigan. To the north, the lake is flanked by long bays, including Green Bay in the northwest, and Grand Traverse and Little Traverse bays in the northeast. The word michigan is believed to come from the Ojibwe ᒥᓯᑲᒥ (michi-gami or mishigami), meaning "great water".

Lake Huron (/ˈhjʊərɒn, -ən/ HURE-on, -⁠ən) is one of the five Great Lakes of North America. It is shared on the north and east by the Canadian province of Ontario and on the south and west by the U.S. state of Michigan. The name of the lake is derived from early French explorers who named it for the indigenous people they knew as Huron (Wyandot) inhabiting the region.Hydrologically, Lake Huron comprises the eastern portion of Lake Michigan–Huron, having the same surface elevation as Lake Michigan, to which it is connected by the 5-mile-wide (8.0 km), 20-fathom-deep (120 ft; 37 m) Straits of Mackinac. Combined, Lake Michigan–Huron is the largest freshwater lake by area in the world. The Huronian glaciation was named from evidence collected from the Lake Huron region. The northern parts of the lake include the North Channel and Georgian Bay. Saginaw Bay is located in the southwest corner of the lake. The main inlet is the St. Marys River from Lake Superior, and the main outlet is through the St. Clair River toward Lake Erie. Lake Huron has a fairly large drainage basin covering parts of Michigan and Ontario. Water flows through Lake Huron faster than the other Great Lakes with a retention time of only 22 years.

The Straits of Mackinac (/ˈmækənɔː/ MAK-ə-naw; French: Détroit de Mackinac) are the short waterways between the U.S. state of Michigan's Upper and Lower Peninsulas, traversed by the Mackinac Bridge. The main strait is 3+1⁄2 miles (5.6 kilometers) wide with a maximum depth of 295 feet (90 meters; 49 fathoms), and connects the Great Lakes of Lake Michigan and Lake Huron. Given the large size and configuration of the straits, hydrologically, the two connected lakes are one body of water, studied as Lake Michigan–Huron. Historically, the native Odawa people called the region around the Straits Michilimackinac.

Three islands form the eastern edge of the Straits of Mackinac; two are populated—Bois Blanc Island and Mackinac Island, while the third, Round Island, is uninhabited and a designated wilderness area. The Straits of Mackinac are major shipping lanes, providing passage for raw materials and finished goods and connecting, for instance, the iron mines of Minnesota to the steel mills of Gary, Indiana. Before the railroads reached Chicago from the east, most immigrants arrived in the Midwest and Great Plains by ships on the Great Lakes. The straits are five miles (8 km) wide at their narrowest point, where they are spanned by the Mackinac Bridge. Before the bridge was built, car ferries transported vehicles across the straits. Today passenger-only ferries carry people to Mackinac Island, which does not permit cars. Visitors can take their vehicles on a car ferry to Bois Blanc Island.