One can do a long traverse of Black Rock, on the face that faces the ocean. I swam by and saw a trail of chalk, so I had to do it. You can either go north to south, or south to north. Going from south to north makes the start/getting out the water easier. The chalk was never more than 10-15 feet above the water. The climbing is pretty fun, but BRING SHOES!!! The lava is very sharp and painful on your feet (I did it barefoot and cut my feet up a little). Bunch of variations possible. The route I did was probably no harder than 5.10. Lots of fun!
Very fun and a good place to snorkel too. The crux is pulling out of the water, after that the climbing doesn't get harder than 5.9. If you are going to do it more than once (and you will) then swim out with your shoes. The rock is so sharp that the shoes helped even when wet. The best part was the tourists jumping over my head while I was climbing.