It's a great idea to make friends with your local tennis pro who may be prevailed upon to give you the old, used court balls that are too dead for tennis but are just right for your lively Lab. Water is a must for a Lab. They love to swim, especially to retrieve the aforementioned tennis balls. Pools require supervised swimming. He won't be able to pull himself up over the side, so he could exhaust himself trying to get out, then drown.
Cracker loves pools, lakes, ponds, puddles.
She enjoys retrieving and goes for recreational swims in our friends' pools. Mud puddles are Lab magnets. Cracker relishes any opportunity to disport herself in cool, clingy slime. Anything we regard as gooey, messy and dirty she sees as puddle-luscious. Luckily for us all, a Lab's coat is relatively self-cleaning.