Lake Superior Fun Facts Largest freshwater lake in the world, one inch of surface water is equal to 553 billion gallons. Superior is the coldest, deepest, and highest in elevation of any of the Great Lakes. Old timers say that Superior doesn't give up her dead. If you go down on Superior, chances are your body will not be found. This is one lake that you need to know what your doing if you play in her waters. Last time Superior totally froze over was 1997. In 2003 the lake almost froze over again, except the western areas along the Minnesota shoreline. Superior is being effected by a drought, lack of normal snow and rainfall accumulations the past four years. This has caused Lake Superior to reach low water levels not seen in recent decades. Lake Superior was conceived 1.1 to 1.2 billion years ago during the mid-continent rift. For over 2 million years Superior was repeatedly inundated with thick flow of lava. During the periods between these flows, the crust down-warped, creating a basin that accumulated sediments until the cycle begun again with the next flood of molten lava. Weather and climate is moderated by Lake Superior, winter is warmer and summers are cooler. This effect is strongest when the winds blow off her waters and is most pronounced along the immediate shorelines and on the slopes that face the lake. Between late spring and late fall the shore can be shrouded in fog when the land surrounding Lake Superior heats up much warmer than the water. This warm season fog occurs when when moisture in the warm air condenses as it flows over the cold lake. Duluth, Minnesota has an average of 52 days of heavy fog each year. Most of Lake Superior shipwrecks occurred during fall storms called "northeasters." These storms build when low pressure systems pass over the lake. Winter temperatures rarely dip below -30°F/-35°C, inland temps however can go well below -30°F/-35°C. During most winters the lake can become 40-95% covered with ice. Length: east-west 350 miles/563 km Width: south-north 160 miles/257 km Elevation: approx. 602 feet/183 meters above sea level Basin population: 425,500+ U.S. citizens and 181,500+ Canadians Shoreline Total: 2,980 miles/4,795 kilometers including island shorelines Water Surface Area: 31,700 square miles/82,100 square kilometers Average Depth: 489 feet Number of fish species: 78 Maximum Depth: 222 fathoms or 1,333 feet, 406 meters, 46 miles southwest of caribou Island or 5 degrees and 25 miles from Grand Island Picture Rocks National Lakeshore. In the area west of Marquette, Michigan. High Water Level: 602.86 feet above sea level in 1876 Low Water Level: 598.23 feet above sea level in 1926 Water Clarity: 65-75 feet of visibility in some areas, average is 24 feet/8 meters Water Volume: 3,000,000,000,000,000 gallons of 440 trillion cubic feet or 10% of the world's fresh water. Enough to flood North and South America to one foot deep. Flushing Rate: 400-500 years for a complete water change Detention Rate: 191 years for a drop of water to remain in the lake Flow Rate Into Lake Huron: 73,7000 cubic feet/2,124 cubic meters per second average Average Water Temperature: 40 ° F/4 ° C Calmest months: June and July Stormy Months: October and November Maximum Wave Height Recorded: 51 feet near Whitefish Bay Yearly average number of vessels that visit the Duluth/Superior port: 1000 Yearly average visitor count: 3-4 million persons Shipwrecks Recorded: 350 and more than 1,000 lives have been lost. [more shipwreck info] See story about Lake Superior ice coverage March 2009. Duluth Harbor Picture | Grand Marais, Minnesota Harbor Pictures