Most likely the channel is just out past them, or they are close to it,in the pic. I have seen the view of the bluffs beyond, but I have yet to remember where I was, to see the outline. Maybe someone can say where they took the pic. I'm thinkin it's up towards Frontenac, N. of Lake City,MN. Looking East towards Wisconsin.
The Postcard pic is still nice to look at. Makes ya wonder if it was actually fishin' or just one Heck of a party...