I was trying to ford a river once, to retrieve a canoe I'd put into a logjam. Had two friends with me, holding one end of a long rope from shore while I had the other end looped under my shoulders.
Got maybe halfway across before the current was just to strong (and I was too exhausted) to keep my footing anymore - it's just unbelievable how quickly being submerged in cold water and fighting against the current like that sucks the energy out of you.
It was all I could do to keep my head above water and kick myself back to shore, I doubt I'd have been able to drag myself out of the river if I'd been by myself.
And that river (north fork of the Chena) wasn't even glacier fed, like a lot of rivers in Alaska are...