San Diego is great for water activities, including kayaking, sailing, snorkeling or parasailing.
The best place to go kayaking is La Jolla Ecological Preserve, with its seven caves. While kayaking, paddlers often see sea lions, leopard sharks and the paddler may even be lucky enough to see a dolphin. The caves are rich with kelp beds. Snorkeling is also great at the Ecological Perserve, and the lucky surfer will see the elusive giant black sea bass.
The best place to go sailing is the San Diego Bay. Great places to visit, while sailing, include Harbor and Shelter Islands, Point Loma, Cabrillo National Monument along with Coronado Bridge. Many who sail,also love to visit the Maritime museum, which features many old boats to explore.
The best place to go hang gliding is at Torrey Pines, where people have been flying since Limburg first flew. The area has gentle winds and great cliffs, which are great for any experience level.
The best place to go parasailing is the west end of Mission Bay, which is also a great location for rowboats and is located right next to Sea World. Mission Bay is also a great place to sail a catamaran.
So whatever sport you desire, San Diego is a great place to explore.