Almost any beach in the county is great for running at low tide. Make sure to consult the tide charts in the local newspaper or your run may turn into a swim. The most popular run downtown is along the Embarcadero, which stretches for 2 mi around the bay. There are uncongested sidewalks all through the area, but the alternative in the downtown area is to head east to Balboa Park,Morley Field where trails snake through the canyons. Joggers can start out from any parking lot, but it's probably easiest to start anywhere along the 6th Avenue side. Entry to the numerous lots is best where Laurel Street connects with 6th Avenue. There's also a fitness circuit course in the park's area. Mission Bay is renowned among joggers for its wide sidewalks and basically flat landscape. Trails head west around Fiesta Island, providing distance as well as a scenic route. Del Mar has the finest running trails along the bluff; park your car near 15th Street and run south along the cliffs for a gorgeous view of the ocean. The Mission Beach boardwalk is a great place to run while soaking up the scenery and beach culture. Organized runs occur almost every weekend. They're listed in Competitor magazine, which is available free at bike and running shops. Roadrunner Sports (5553 Copley Dr., San Diego. 858/974-4475. www.roadrunnersports.com) has all the supplies and information you'll need for running in San Diego. Don't run in bike lanes!