This is some more of the shoreline of Lake Mille Lacs, taken from the same spot as my last photo.
Lake Mille Lacs is home to the smallest wildlife refuge in the United States, covering two small islands (just over half an acre in total) where common terns, ring-billed and herring gulls, and double-crested cormorants breed. We also saw a cormorant that day; I could only find reference to double-crested cormorants, but in this case the coloring doesn’t seem to line up. Maybe its a juvenile?
Update: This is actually a female Common Merganser.