Just like volleyball only in a swimming pool
Swimming pool Volleyball net Volleyball
This game requires a special volleyball net which is stretched across the center of a rectangular swimming pool. Players can participate by standing (assuming the pool has a large shallow area) or by sitting on inner tubes. Two on two or three on three works well. Rules of regular volleyball apply. One team serves and the other team has three hits to get it over the net. If the ball touches the water before going over the net, it is returned to the other team. If a serving team can keep the opposing team from returning the ball, they score a point. The ball must stay within the pool boundaries or else a side out results. First team to 15 wins.