They actually float pretty well. I was setting up a low sided 60gallon stock tank for outdoor water and put bricks in it so anything that got in could get out without drowning. Hearing everyone say chickens can't swim I decided to make sure no one would drown by doing a supervised test with 2 small bantam hens. I plopped the first one in and while she complained greatly she most definitely did not sink. She did not even flap. She floated there until she drifted over near the bricks and then hopped out. I repeated the test with the other hen with the same results. They floated there for more than 5mins without any sign of sinking. I can't say they actually swim well cause they made little attempt to move a certain direction but at least some of them do actually float just fine.
Actually, I wonder if they might like a small kiddie pool in the heat of summer, with just a few inches of water in it. Of course, I never see them in puddles or anything...maybe water just isn't their thing...
I've had my barred rocks and buff orphingtons crash land in my swimming pool in the back yard while attempting to fly over it. They float like a duck and don't seem too panic. On each occassion, they have paddled over to the side of the pool, hopped out and shaken themselves off like a dog. That said, they have each done it ONCE and don't seem to want to get back in. I've taken my Alpha Chicken, a Buff Orph hen on an inflatable raft around the pool...she seemed to like it.
Mine love puddles. They have a water pan that is 5" deep by 20" wide by 42" long and in the heat of the day they go wading in it.
I also try and go out right after lunch and wet the ground in their run for them. After I do that, while it is still damp, they all take themselves a dust bath. Yesterday I was wishing that I had my camera because I had about 40 teenage chickies all laying around taking their bath, all at once!