Mission Trails Regional Park (1 Father Junípero Serra Trail, Mission Valley, 92119. 619/668-3281. www.mtrp.org) has a huge quantity of bouldering, top-roping, and single-pitch climbs. With plenty of belay stations and holds that are regularly changed, the three locations of Solid Rock Gym (2074 Hancock St., Old Town, 92110. 619/299-1124. www.solidrockgym.com) appeal to all skill levels with indoor top-roping, bouldering, and lead climbing areas. In addition to day-use fees they rent equipment and offer lessons. Vertical Hold Sport Climbing Center (9580 Distribution Ave., Mira Mesa, 92121. 858/586-7572. www.verticalhold.com) is the largest full-service indoor rock-climbing gym in Southern California. It offers lessons, equipment rentals, and party packages.