<Li> The Welland Canal, bypassing the Falls, connects Lake Erie to Lake Ontario . </Li> <Li> The Saint Lawrence River and the Saint Lawrence Seaway connect Lake Ontario to the Gulf of St. Lawrence, which connects to the Atlantic Ocean . </Li> <P> Lakes Huron and Michigan are sometimes considered a single lake, called Lake Michigan--Huron, because they are one hydrological body of water connected by the Straits of Mackinac . The straits are 5 miles (8 km) wide and 120 feet (37 m) deep; the water levels--currently at 577 feet (176 m)--rise and fall together, and the flow between Michigan and Huron frequently reverses direction . </P> <Ul> <Li> Lake Nipigon, connected to Lake Superior by the Nipigon River, is surrounded by sill - like formations of mafic and ultramafic igneous rock hundreds of meters high . The lake lies in the Nipigon Embayment, a failed arm of the triple junction (centered beneath Lake Superior) in the Midcontinent Rift System event, estimated at 1,109 million years ago . </Li> <Li> Green Bay is an arm of Lake Michigan, located along the south coast of the Upper Peninsula of Michigan and the east coast of Wisconsin . It is separated from the rest of the lake by the Door Peninsula in Wisconsin, the Garden Peninsula in Michigan, and the chain of islands between them, all of which were formed by the Niagara Escarpment . </Li> <Li> Lake Winnebago, connected to Green Bay by the Fox River, serves as part of the Fox--Wisconsin Waterway and is part of a larger system of lakes in Wisconsin known as the Winnebago Pool . </Li> <Li> Grand Traverse Bay is an arm of Lake Michigan located on Michigan's west coast, being one of the largest natural harbors in the Great Lakes . The bay has one large peninsula and one major island known as Power Island . Its namesake is derived from when Jacques Marquette crossed the bay from Norwood to Northport calling it La Grande Traversee . </Li> <Li> Georgian Bay is an arm of Lake Huron, extending northeast from the lake entirely within Ontario . The bay, along with its narrow westerly extensions of the North Channel and Mississagi Strait, is separated from the rest of the lake by the Bruce Peninsula, Manitoulin Island, and Cockburn Island, all of which were also formed by the Niagara Escarpment . </Li> <Li> Lake Nipissing, connected to Georgian Bay by the French River, contains two volcanic pipes, which are the Manitou Islands and Callander Bay . These pipes were formed by a violent, supersonic eruption of deep - origin . The lake lies in the Ottawa - Bonnechere Graben, a Mesozoic rift valley that formed 175 million years ago . </Li> <Li> Lake Simcoe, connected to Georgian Bay by the Severn River, serves as part of the Trent--Severn Waterway, a canal route traversing Southern Ontario between Lakes Ontario and Huron . </Li> <Li> Lake St. Clair, connected with Lake Huron (to its north) by the St. Clair River and with Lake Erie (to its south) by the Detroit River . Although it is 17 times smaller in area than Lake Ontario and only rarely included in the listings of the Great Lakes, proposals for its official recognition as a Great Lake are occasionally made, which would affect its inclusion in scientific research projects, etc., designated as related to "The Great Lakes". </Li> </Ul>

The main outlet to the sea for the great lakes is the st. lawrence river