I was watching this mute swan bathing, and I knew he was likely to rear up like this, because it's very often the last stage of the bathing ritual before they shake all the feathers back into place, give a few flicks of the tail, and swim off looking pleased with themselves. So I kept watching and shooting, because even after all the times I've seen it I still don't know quite how they do it. And I'm still not much wiser, to be honest: the previous shot in the sequence shows him driving down quite hard with his wings against the surface of the river, which must help the initial lift, but now he's raised the wings and his quite considerable bulk off the water, which is deep and flowing very fast at the moment. I suppose he must be treading water, and the rest is down to core muscle power - and that seems to me to be a triumph of will over gravity.
By the way, if you're thinking That water looks especially filthy - you're right. The Avon is in spate from a combination of snow melt and rain, and already breaking its banks in quite a few places, and a large quantity of soil and debris has been either washed into it or churned up; the fishermen on the south bank looked quite fed up at all the rubbish they were snagging today.
And if you're also thinking It looks as though it was raining when she took this - you're right again. If it keeps doing it, as the forecast says it will, the swans will probably be able to come to us by about the middle of next week.