San Diego's got a plethora of lakes to chose from, and a ton of activities to do while you're there. Check out this list of San Diego's lakes: http://dguides.com/sandiego/attractions/lakes/

San Diego has a great lake off of I-15 & Mira Mesa Blvd. called Miramar Lake. It is a one of the great San Diego attractions that you will truely enjoy. You can go jogging & biking around the lake and go fishing as they stock the lake with rainbow trout year round.