Water, Water by Cary Fagan

One morning Rafe wakes up to discover his bedroom is floating in a vast sea of water. Alone with only his dog for company, Rafe adapts to this strange new world by fishing cans of food out of the water and keeping watch. Boxes float by, as does a woman, playing her cello. Then, one day, Rafe fishes out a young girl, who joins him in his room - they don't speak the same language, but together they will face this uncertain future.