there's a training club about 40 minutes from my house that put in a dog pool. it's fantastic. heated room, heated water. $15/half hour for the first dog, $7 for the second dog and you get an extra 15 minutes too.
when it was time to go, i couldn't get him to get out! i took the toys away but he still kept jumping into the pool and swimming around, coming back to the very end of the ramp where i couldn't get him without getting in, jumping back in. it made me laugh.