Largest freshwater lake is not the Caspian Sea

Dear Matthew Alice: I have a question all the way from the shores of Lake Erie: What is the largest body of fresh water on the planet? — Bill Gordon, Cleveland, OH

Trying to trip me up with trick questions, Bill? Hoping I’ll say “Caspian Sea" so you can pull some “Gotcha!” routine? Or maybe you’re just settling a bar bet and need some independent corroboration. I suspect you already know the answer to this one, as you lounge smugly on the shores of Lake Erie. Anyway, I say to those who may not already know, the Great Lakes constitute the largest body of fresh water on the planet. The five connected lakes (Erie, Huron, Superior, Michigan, and Ontario) cover about 95,000 square miles. By definition, a lake is a single body of water surrounded by land, so the quintet really should be called “the Great Lake.”

That vast Eurasian pool called the Caspian Sea is bigger (143,244 square miles), but it’s not fresh water. (Fresh water is 0.3 parts per thousand of salts or less; on average, ocean water is about 35 parts per thousand; average for the Caspian Sea is about 13.) It’s the largest lake in the world and also the largest enclosed body of salt water. The Caspian and three of its neighboring seas (Aral, Azov, and Black) are the remains of a single ancient saltwater basin.

In its component parts, the Great Lakes contain three of the world’s five largest freshwater lakes — Superior (the world’s largest, 31,700 square miles), Huron, and Michigan (fourth and fifth, respectively). Your little bit of heaven ranks eleventh. “Ranks” is the operative word here. I can’t say that Erie exactly qualifies as “fresh water.” Any lake so polluted that it once actually caught fire could never be called “fresh.”