The object is to be the 1st player to score 21 points.
You score points by making baskets like in basketball, but this game uses an innertube instead of a hoop.
2 points for a goal scored and then free throws are awarded...as many as can be made (from st least 20 feet away).
Play resumes on a fee throw if the ball hits the tube or the water. Goal tending/moving is allowed but not on fee throws.
The guys I work with made this game up yesterday when we were hanging out at the pool.
Add or subtract rules to suit your tastes.