Don’t know about Swans, but I was attacked by a Canadian goose when I was 6 years old while standing in chest deep water. That Goose would have eaten my lunch if it hadn’t been for Mom. Did you know Geese have teeth?
Yes... or at least it seems like it. I had my grandson at a pond feeding ducks when a goose came along and went after my grandson. I just got between them and got bit in the ass. No blood, but it hurt.
A swan is a lot bigger than a goose. If it were really a fight to the death on land, I'd beat the swan no doubt. But in the water, I'm not so sure. They are nasty critters.