Just How Big is Lake Superior?

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Lake Superior vs. East Coast

Steve Colman, now retired from the University of Minnesota Duluth's Large Lakes Observatory, uses this comparison with the U.S. East Coast to explain the size of the Big Lake.

Raising Lake Superior's level by a single inch requires 551 billion gallons of water, but even that enormous sum is a mere drop in the Big Lake bucket.

It's the world's largest freshwater lake by surface area – 31,700 square miles (82,100 square kilometres), or roughly the size of Maine – and holds 10 percent of the world's surface fresh water. (By volume, it's the third largest, behind Lake Baikal in Siberia and Lake Tanganyika in eastern Africa.) Lake Superior's 3 quadrillion gallons are enough to cover both North and South America under a foot of water.

Here's another (preposterous) way to think about it: Downing half a gallon of water daily, it would take you 16.4 trillion years to drink Lake Superior. Or the entire world population of 7 billion people, each person drinking half a gallon per day, could together polish off Lake Superior in 2,348 years.

The Big Lake holds as much water as all of the other Great Lakes combined plus three more Lake Eries. To reach its deepest point, you'd need to descend 1,276 feet – about the distance of a ride down from the top floor of Chicago's 108-story Willis Tower.

Lake Superior is so large and so deep that its retention time – about how long an average drop of water remains in the Lake – is 191 years. For Lake Michigan it's 99 years, Huron 22, Ontario 6 and Erie just 2.6 years. No wonder ours is called Superior.

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Superior Volume

Lake Superior has as much water as the rest of the Great Lakes combined – plus three more Lake Eries.

More facts

Length: 350 miles (560 kilometres)

Width: 160 miles (260 kilometres)

Volume: 3 quadrillion gallons, or 2,900 cubic miles (12,100 cubic kilometres)

Shoreline: 1,826 miles (2,938 kilometres)

Average depth: 483 feet (147 metres)

Maximum depth: 1,276 feet (389 metres)