I’ve been to Lake Superior. We drove the North Shore from Duluth, Minnesota to Thunder Bay, Ontario, Canada, then crossed back over the border at International Falls, Minnesota. It was spectacular!
I've waded in it. Not very deep, though! The balefully-cold water begins at six inches, the water that will stop your heart starts at 18 inches. And that's in August, when it's all warmed up!
Lived in/near Duluth for a year and a half in 1959-60. The old airbase I lived on is now a state penal institution.