Lake Huron in the context of "Soo Locks"

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 Superior is a lake in central North America. The northernmost, westernmost, and highest of the Great Lakes, Lake Superior straddles the Canada–United States border with the Canadian province of Ontario to the north and east and the U.S. states of Minnesota to the west and Michigan and Wisconsin to the south. It is the largest freshwater lake in the world by surface area and the third-largest freshwater lake by volume. It drains into Lake Huron via St. Marys River, then through the lower Great Lakes to the St. Lawrence River and ultimately the Atlantic Ocean.

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 Michigan–Huron (also Huron–Michigan) is the body of water combining Lake Michigan and Lake Huron, which are joined through the 5-mile-wide (8.0 km), 295-foot-deep (90 m), open-water Straits of Mackinac. Huron and Michigan are hydrologically a single lake because the flow of water through the straits keeps their water levels in overall equilibrium. Although the flow is generally eastward, the water moves in either direction depending on local conditions. Combined, Lake Michigan–Huron is the largest freshwater lake by area in the world. Lake Superior is larger than either individually, so it is counted as the largest of the Great Lakes when Lake Michigan and Lake Huron are considered separately.

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.

The Great Lakes Waterway (GLW) is a system of natural channels and artificial locks and canals that enable navigation between the North American Great Lakes. Although all of the lakes are naturally connected as a chain, water travel between the lakes was impeded for centuries by obstacles such as Niagara Falls and the rapids of the St. Marys River.

Its principal civil engineering works are the Welland Canal between Lakes Ontario and Erie, and the Soo Locks between Huron and Superior. Dredged channels were constructed in the St. Marys River, the Detroit River, Lake St. Clair and the St. Clair River between Huron and Erie. Usually, one or more U.S. Coast Guard icebreakers help keep the water passage open for part of the fall and early winter, although shipping usually ceases for two to three months thereafter. The St. Lawrence Seaway allows navigable shipping from the GLW to the Atlantic Ocean, while the Illinois Waterway extends commercial shipping to the Mississippi River and the Gulf of Mexico. The Great Lakes Waterway is co-administered by the governments of Canada and the United States.

The Province of Upper Canada (French: province du Haut-Canada) was a part of British Canada established in 1791 by the Kingdom of Great Britain, to govern the central third of the lands in British North America, formerly part of the Province of Quebec since 1763. Upper Canada included all of modern-day Southern Ontario and all those areas of Northern Ontario in the Pays d'en Haut which had formed part of New France, essentially the watersheds of the Ottawa River or Lakes Huron and Superior, excluding any lands within the watershed of Hudson Bay. The "upper" prefix in the name reflects its geographic position along the Great Lakes, mostly above the headwaters of the Saint Lawrence River, contrasted with Lower Canada (present-day Quebec) to the northeast.

Upper Canada was the primary destination of Loyalist refugees and settlers from the United States after the American Revolution, who often were granted land to settle in Upper Canada. Already populated by Indigenous peoples, land for settlement in Upper Canada was made by treaties between the new British government and the Indigenous peoples, exchanging land for one-time payments or annuities. The new province was characterized by its British way of life, including bicameral parliament and separate civil and criminal law, rather than mixed as in Lower Canada or elsewhere in the British Empire. The division was created to ensure the exercise of the same rights and privileges enjoyed by loyal subjects elsewhere in the North American colonies. In 1812, war broke out between Great Britain and the United States, leading to several battles in Upper Canada. The United States attempted to capture Upper Canada, but the war ended with the situation unchanged.

The Flint water crisis was a public health crisis from 2014 to 2019 which involved the drinking water for the city of Flint, Michigan, being contaminated with lead and possibly Legionella bacteria.

In April 2014, during a financial crisis, state-appointed emergency manager Darnell Earley changed Flint's water source from the Detroit Water and Sewerage Department (sourced from Lake Huron and the Detroit River) to the Flint River. Residents complained about the taste, smell, and appearance of the water. Officials failed to apply corrosion inhibitors to the water, which resulted in lead from aging pipes leaching into the water supply, exposing around 100,000 residents to elevated lead levels. A pair of scientific studies confirmed that lead contamination was present in the water supply. The city switched back to the Detroit water system on October 16, 2015. It later signed a 30-year contract with the new Great Lakes Water Authority (GLWA) on November 22, 2017.

René-Levasseur Island is a large island in the centre of Lake Manicouagan in Quebec, Canada. Its highest peak is Mount Babel, at 952 m (3,123 feet), which is contained in the Louis-Babel Ecological Reserve. With a total area of 2,020 km (and a diameter of 50.7 km), the island is larger in area than the annular lake in which it is situated. René-Levasseur Island is the world's second-largest lake island (the largest is Manitoulin Island in Lake Huron).

The geological structure was formed by the impact of an asteroid 214 million years ago. The asteroid is believed to have been about 5 km in diameter, and would have hit Earth at a speed of 17 km/s, the fifth most powerful known impact that Earth has seen. The impact of the asteroid formed a crater roughly 100 km in diameter, the centre of which forms the island known today. It became an artificial island when the Manicouagan reservoir was flooded in 1970, merging two crescent-shaped lakes: Mouchalagane Lake on the western side and Manicouagan Lake on the eastern side.