Throw a large amount of pennies (depending on the number of kids)
into the pool. Remember to count them or the lifeguards/cleaners may
not see the humour in finding errant pennies. Cover about a third
of the pennies with white out. Teams hunt for pennies. Those with
a white mark are worth extra points. The team with the most points
(and white pennies) wins.
Variations: Try this
with individual swimmers allowed to take only one breath.