Historic summer playground. A sandy beach built up over the centuries by Mississippi River currents that  flow unseen  through the normally placid 40-square mile Lake Pepin on the Minnesota-Wisconsin border. At places the lake is 60 feet deep. Image: Bell Museum diorama at the University of Minnesota. Painted by Francis Lee Jaques and Walter J. Breckenridge in 1940 as background to illustrate 20 native bird species.

What went wrong: Undertow? Steep drop-off?

FRONTENAC, Minn. —  The body of a swimmer was recovered from the upper end of Lake Pepin off Long Point. Goodhue County Sheriff Marty Kelly declined to release the man’s name pending an autopsy but said he was 56 years old. The man went under about 3:15 p.m. on Saturday. Witnesses said a 13-year-old girl, who was   a family friend, had waded out to join him. Both ended up in trouble. The girl suddenly flailed in distress. Nearby boaters rescued the girl. The man didn’t resurface.