Swimming is great exercise, but it's tough to do laps if you don't have a big, Olympic sized pool. Well, screw laps. You don't need no stinking laps. Just get a Pool Treadmill.
It's a big ol' device that sits at the end of your pool and makes it so you can swim in place by creating a moving current. You'll get all the exercise of laps without ever having to stop at the edge of the pool and turn around. Sure, it's a bit pricey at $4,000, but doesn't that seem totally worth it for the ability to never have to turn around at the edge of your pool again?