Not really in the OC, but not too far away. The Palos Verdes peninsula has amazing ocean views. It gets crowded, and there isn't a lot of real trail, but you can accumulate some good gain climbing up/down from the water.
1 A foggy, but panoramic, view to start the morning. Fortunately the fog would soon clear.
2 Heading down to sea level.
3 Fantastic views. And you can control exactly how much gain you want by how many times you run down from the bluffs and then back up again.
4 I didn't stay long enough to explore the sea life, but it's supposed to be a good spot to find some.
5 A very creative collection of cairns.
6 Back up on the bluffs. Here's a good look at one of the steep trails switch-backing down to the water.
7 Looking back at the [bleep] National Golf Club, where the trailhead is unfortunately located. I can't even mention the name here.
8 Unquestionably some of the best ocean views in SoCal.
9 One of the trails heading up from the water to the bluffs. It's a great climb.