Keep it Dry
Give each player an object that becomes warped when wet, such as a cotton ball. Each player must walk off the end of the diving board, in succession, and into the pool while holding the object. If the object becomes wet then the person is eliminated. Have a judge inspect the item when the player exits the water to get back in line. The last person with a dry item wins the game.
Beach Ball Relay
Assign one person to stand in the water opposite the diving board. The rest of the players take turns jumping off the diving board. When one person jumps into the air, the person standing in the water tosses him a beach ball. If the jumper catches the ball before he hits the water, he advances to the next round. Keep playing until only one person is left, who is the winner. For added fun and entertainment, have the jumper perform acrobatics in the air, such as touching his toes, before catching the ball.
Hurdle Jumping
Place a pool noodle in the water one foot in front of the diving board. Have each player jump off the diving board and over the noodle. Each player that clears the noodle without touching it progresses to the next round. For the second round, move the noodle an additional foot away from the board. Continue moving the noodle for every round that the players reach. The person to clear the farthest noodle hurdle wins the game.