Near Norwich there's a newish country park (Whittlingam) made from old gravel workings. A small lake was given a sandy beach and an area buoyed off and kept weed clear for paddling and swimmimg. It was very popular. A couple of lads, strangers who apparently couldn't read English and seemingly were ignorant of what the buoys and ropes were for, swam in the wrong area where it was weedy - and one drowned. The little lake was immediately fenced off - and still is.
Last summer a beauty spot near Kings Lynn, again an old gravel working with a beach, saw a similar tradgedy when a local bloke drowned. At least this time access hasn't been banned.
I've swum in some beautiful places and love the silky feel of proper water but I think if wild swimming is going to be an accepted pastime much more education is needed about the dangers of cold water, underwater hazards, depth, currents, etc.