Akshually, Michigan-Huron is a single lake, hydrologically speaking of course, which has 1.5 times the surface area of Lake Superior.
But Superior still manages to contain 1.5 times the water volume in just 66% of the surface area, comprising 10% of the surface fresh water on planet earth. That's one deep boi. Aptly named I must say
If you make that argument to Midwesterners at best you will be noggied, have your underwear pulled over your head, and all your linch money taken.
At worst the Cost Guard will come give you a stern talking to since international treaties have determined that Lake Michigan is an entirely US owned body of water that Candad has to keep their dirty paws off of.
Oh yeah, big time. I don't think any of the great lakes would actually fit that description though. The problem with warm lakes is that there's usually a lot more biological activity going on, so the water tends to be much less clear.
I'd prefer to swim in a cold, clear lake instead of a warm, murky lake any day of the week. That's how you get infected by one of these bad boys.