My wife's family has had a ton of Goldens. One of them apparently didn't want to swim at the start. Her father had the bright idea to tie its collar to their other golden at the time. Threw a toy into the water and naturally the one that knew how to swim ran in to fetch it and yanked the other one in with him. The one that didn't "know" how to swim proceeded to attempt to sit on the other to stay afloat and almost drowned the poor pooch. Thankfully my father in law did manage to rescue them, but I don't think he tried that again.
I had a Labrador retriever that didn’t know how to swim. When he was a puppy, he fell off a dock while we were trying to teach him to swim and he refused to try to swim after we’d gotten him back to shore. (We weren’t trying to teach him to swim from the dock. We were taking in the view before heading back to shore and he misstepped.)
He loved water the whole rest of his life, but would only go where he could stand.