The Great Lakes boast 6 quadrillion gallons of fresh water which is one-fifth of the world's fresh surface water (only the polar ice caps and Lake Baikal in Siberia contain more). The Great Lakes are 95 percent of the U.S. supply.
Spread evenly across the continental U.S., the Michigan Great Lakes would submerge the country under about 9.5 feet of water.
Lake Erie, Lake Superior, Lake Huron, Lake Michigan and Lake Ontario
More than 94,000 square miles/244,000 square kilometers of water (larger than the states of New York, New Jersey, Connecticut, Rhode Island, Massachusetts, Vermont, and New Hampshire combined, or about 23 percent of the province of Ontario). About 295,000 square miles/767,000 square kilometers in the watershed (the area where all the rivers and streams drain into the lakes).
United States and Canada -- 10,900 mi/17,549 km (including connecting channels, mainland and islands). The Great Lakes shoreline is equal to almost 44 percent of the circumference of the earth, and Michigan's Great Lakes coast totals 3,288 mi/5,294 km, more coastline than any state but Alaska.
References: Great Lakes Basin brochure, 1990, Michigan Sea Grant
Lake Michigan, the second largest Michigan Great Lake by volume with just under 1,180 cubic miles of water, is the only Great Lake entirely within the United States.
Lake Erie is the smallest of the Michigan Great Lakes in volume (119 cubic miles) and is exposed to the greatest effects from urbanization and agriculture. Measuring 241 miles across and 57 miles from north to south, the lake's surface is just under 10,000 square miles, with 871 miles of shoreline.
Lake Ontario is similar to Lake Erie in length and breadth (193 miles by 53 miles). Yet with its greater average depth (approximately 283 feet), Lake Ontario holds almost four times the volume (395 cubic miles) and has a retention time of about 6 years.
Lake Huron is the third largest of the Michigan Great Lakes by volume, with 850 cubic miles of water. Lake Huron is hydrologically inseparable from Lake Michigan, joined by the wide Straits of Mackinac.
Not only is Lake Superior the largest of the Michigan Great Lakes, it also has the largest surface area of any freshwater lake in the world. It contains almost 3,000 cubic miles of water, an amount that could fill all the other Great Lakes plus three additional Lake Eries.
The Great Lakes Circle Tour is a designated, scenic road system connecting all of the Great Lakes and the St. Lawrence River.
The Circle Tour, established by the Great Lakes Commission in cooperation with its eight member states and the province of Ontario, promotes travel and tourism along the shores of "North America's Fresh Coast."