yes like any other ducks they can swim. It is best to wait until they have some feathering coming in and then only supervised for short periods of time, but our Trouts love the kiddie pools!
In fairness, although the ducks themselves smell lovely, if their area is too small or their run is not regularly cleaned, it does stink.
And they do make a mess. Its absolutely incredible to me that ducks can make such a mess of their pen/food/water and still look as sleek and well groomed as if they've just been to the salon.
All that said, the ducks are by far my favorite birds in our flock! They're so much more fun than chickens or turkeys.