Waterfall Cliff is a popular climbing crag in Castle Rock State Park that offers a collection of about 15 fun routes ranging from 5.6 to 5.12b, with many featuring easy top-rope anchors. About 1 mile from the main entrance to the park, the crag is easy to find and the approach is a nice hike, though it is rather longer than you'll find across the street at Indian Rock. With its proximity to Silicon Valley and generous selection of approachable climbs, Waterfall Cliff is a great choice for spending a day at the crag.
The waterfall observation platform is the landmark for orientation at Castle Rock Falls: You can't miss it from the trail, and it offers wonderful views of both the immediate area and the beautiful park surrounding it. The waterfall creek divides the climbing area into two halves. Immediately below the platform is a large, sheer face that hosts the aptly-named The Falls (5.10a), which is most easily accessed by rappelling from the supports of the platform. In fact, this rappel is itself a popular attraction, with many adventurers coming only for the descent and choosing to hike, rather than climb, back to the anchor. A 60-meter rope is just long enough to make this rappel, so be sure to build your anchor at the very bottom of the support that is closest to the cliff face.
On the other side of the creek from the observation platform is the crag named Waterfall Cliff, which is where most of the routes in this area reside. The trail across the creek begins just before reaching the observation platform that is next to an obvious sign warning "Danger: Sheer cliff, stay back." Generations of climbers have promptly ignored this sign and stamped out a footpath to the creek. Traction on the trail is marginal, so wear sturdy hiking shoes or boots. Once on the other side, follow the trail up, around, and down to the generous belay station at The Layback (5.6). If you're looking to top rope, consider getting your bearings around the face of Waterfall Cliff before hiking back up and looking for the anchors. The easiest, safest anchors to reach are for The Layback and Clean Corner (5.8), though the anchor for Putrefaction (5.11b, or 5.10ish if you omit the crux roof move), the next route nearer the creek from The Layback, is also reachable. A stout tree is available behind these anchors for rigging basic personal protection if desired.
Other classics for Waterfall Cliff include Clamydia (5.12a), Anti-Christ (5.11d), and Greeboo (5.10a). The local favorite climbing guidebook, Bay Area Rock, covers the crag well.
Free parking is available on Skyline Boulevard just south of the main park entrance, while parking in the lot inside the main entrance is available with a $10 day pass. Consider carpooling, as both paid and free parking fill up quickly. You will have the best luck getting on the routes you want if you are able to make it to the crag during the week. Otherwise, bring a sandwich and enjoy a large belay area in a pleasant outdoor setting as you wait for your turn to climb.