UNDERWATER SWIMMING: Give a pair of flippers and a glass of water to each team. The first player stands at the start-line, gets on the flippers, takes the glass of water and lifts it above the head. So he/she is "under the water". At the signal the players begin to move forwards. On having covered the fixed distance the first "submariner" passes the flippers and the glass to the next player. If the water spilled from the glass after the first run, add some more water.
DUCK POND: Put plastic ducks in water and the children pull out a duck and get the prize associated with that duck. You could put numbers or shapes on the bottom of the ducks.