As mentioned above, Resort Watersports is the place to rent everything from kayaks to wave runners. They rent sail boats too. Call to reserve boats and for more information. Here's a club and school that has different levels for novice, experienced and extremely experienced sailors. The club's location is right on the harbor.
Many Insiders visit the club for drinks after a day's sail.
It's a beautiful location to lounge and watch the sun set. The good news is that San Diego has some excellent locations for scuba diving. The bad news is that you must be a certified diver in order to get your tanks filled and legally dive. If you're in town for a week or so, you can get certified in as little as four days and then be able to discover and explore the fascinating underwater world. However, even though the intrepid diver can find lots of interest in local waters, most scuba divers head elsewhere.