Graham is not terribly playful, but one of his favorite things to do outdoors (becides tracking down and killing small fuzzy animals, which I am working on) is fetching a stick in the water. He could play that game for hours, and it's good excersise. If your dog shows little fear of water, and it shows an interest in retreiving, and it has desire to please you, try seeing if it would like to fetch sticks that you throw in the water for it.