La Jolla Cove is the quintessential San Diego beach dive and snorkeling site. If you’re only in town for a day or so  and only have one dive to make, this should be it.  This rocky-bottomed cove lies within an ecological  preserve  and  will allow you to  see a lot of creatures you’d otherwise only be able to find offshore in the kelp beds. To dive this site, you should arrive REALLY early in the morning to get yourself a parking spot near the grassy changing area and bathrooms. Next, just suit up, walk down the stairs to the beach, and have at it. You’ll start seeing marine life immediately and have a lot of fun.