The Great Lakes of Superior, Huron, Michigan, Erie and Ontario hold about 6 quadrillion gallons of water -- enough to submerge the continental United States 9.5 feet under.
Only one of the lakes, Lake Michigan, is entirely in the U.S.
The Great Lakes form the world's largest body of fresh water in surface area.
They contain nearly 20 percent of the world's fresh surface water.
Lake Superior is the deepest of the five lakes, with the deepest point being 1,333 feet. Lake Erie's deepest point is 210 feet.
Lake Superior is also the largest in area, covering 31,700 square miles. Lake Huron is next with an area of 23,000 square miles, followed by Lake Michigan at 22,300 square miles.
The total area of the Great Lakes is 94,000 square miles, a bit larger than the states of New York, Connecticut, Rhode Island, Massachusetts, Vermont and New Hampshire combined.
The coastline of the Great Lakes is 10,900 miles. This includes connecting channels and islands. Lake Huron has the longest coastline, including islands.
The Great Lakes were formed by retreating glaciers over 14,000 years ago.
There are 4.2 million registered recreational boats in the Great Lakes states - one for every three in the U.S.
More than 60 percent of Great Lakes shipping traffic travels to and from overseas ports. Iron ore, coal, grain and steel make up about 80 percent of the Great Lakes cargo each year.
The St. Lawrence Seaway System was completed in 1959, linking the Great Lakes ports to the global market.
It takes 8 and one half days to sail from where the St. Lawrence Seaway empties into the Atlantic Ocean to Duluth, Minnesota, the western-most Great Lakes port.
Sources: World Almanac, World Book, Associated Press, Great Lakes Information Network, Friends of the Great Lakes