I went rock climbing the other night and it was a lot of fun and a good workout to boot! I went to a place called Pacific Edge in Santa Cruz, which is an indoor rock climbing gym. While not quite the same as climbing a real rock, indoor rock climbing offers a wide range of climbing experiences from very challenging to beginner.
Pacific Edge itself offers bouldering, top-rope wall and lead wall climbs, with plenty of overhangs and a few cracks to round out the climbing. They also offer a weight room, cardio equipment, and yoga classes. You can take climbing classes as well. If you are in the Santa Cruz, California area and are looking for a fun way to get a workout in, try them. You will have fun.