I often went swimming in the Rhine as a child in Germany, around 50km south of Frankfurt. We had a rubble beach and the river only was 1m deep for half its wid

I often went swimming in the Rhine as a child in Germany, around 50km south of Frankfurt. We had a rubble beach and the river only was 1m deep for half its width. Was pretty nice. The water was colder than in the lakes and it came with a natural counter-current system, so you could swim in-place.