I only have a few dives in the Malibu/Ventura area and don't dive San Diego enough, so I'll stick to southern L.A. County/O.C. and leave the Northern and Southern sites to the more knowledgable.
Veteran's Park, Redondo Beach.
Beach diving doesn't get any easier than this. Plenty metered parking spaces, restrooms(closed after Sunset), cold(very)freshwater showers, usually low surf and quick access to deeper water. Sand environment underwater with Rays, Sea lions, octopus, squid, various fish and nudibranchs plus the easiest access to the Redondo underwater canyon. Shops, restaurants on the pier and dive shops close by.
Topaz Street Jetty.
At the base of the stairs is a relatively short jetty where you'll find lobsters at night and typical SoCal fish foraging during the day. At the end of the jetty you can take a heading for the old pier pilings where the marine life congregates. Still further is the edge of the canyon. A single freshwater shower is next to the Lifeguard stand.
Malaga Cove, Torrance, P.V.
Shallow rocky reef with kelp, lobsters and the typical reef denizens. The main access is by paved road down from the parking lot at the Malaga Cove School. Check out conditions from the gazebo in the lot before hiking down the trail. Water entry can be made over the rocks at the end of the pavement if the surf is down or continue to the end of the dirt trail at RAT Beach(Right After Torrance)for a sand entry and long surface swim.
Flat Rock.
For the thrillseeker in all of us. Great diving with parallel reefs seperated by sand channels. Lobster, Black Sea Bass, Batrays. The trail is long and steep, but easily passable. Enter from the cove and surface-crawl over very shallow water, less than one foot. Another option is to continue on the goat path to the point and enter into 10-12 feet of water. Must be sure-footed and you should avoid this entry during high surf.
Christmas Tree Cove.
Usually has the best vis on the peninsula. Steep dirt trail. Great shallow snorkeling to the right of the trail end. The best diving is outside the cove in 30-80 feet. Cool overhangs, kelp, lobsters, occasional pelagics and Gray whales close to shore here.
Marineland.
One of my favorite sites in SoCal. Fairly easy walk down a paved/dirt road to a rocky beach. There are three main options here. If the surf is flat you can enter the water on the far right side of the property. Experience with rocky entries is a must. In light surf you can sit on a rock, put your fins on and when the next wave comes in, ride it out. Keep your hands ready to fend off a few shallow boulders on the way out. There is a large, healthy reef here that fades away around 70 feet. Most divers who enter at this point take a compass heading for the small cove before dropping down for an easier exit. If the surf is up at the point, enter from the cove. There is a large reef system to the left of the cove that extends offshore to about 50 feet and you can follow it into the next cove over. To the right of the entry point is the beginning of the large reef to the right. You can follow it around, as the line where the reef meets the sand parallels the shoreline. Straight out from the cove is a sandy area where you will find sea pens, sand dollars and halibut.
White Point.
This is one of the only places where you can park near the entry point. Until last year, you could park right at the water's edge. Conditions here vary from zero vis to over forty feet with ten feet being average. Outside the shallow cove are hot water vents. You can smell the sulpher from the cliff above. Nearly every surface is covered by a white fungus. If you swim to the kelp outside the cove you will find the usual reef critters in 25-40 feet.
Crystal Cove (Reef Point) just North of Laguna Beach.
Large pay parking lot with new access close to the beach. Restrooms, showers and some of the best diving in Orange County. Be wary of the plentiful rocks in the surf zone, as well as surfboards when the surf is up. Large reef made up of huge boulders go on forever, well, at least 1/4 mile that I have seen. The usual reef critters are here, as well as sea lions, harbor seals and Moray eels.
Seal Rock/Deadman's Reef, Laguna Beach.
Enter on the right side of the small sandy beach and follow the reef straight from shore. If you move to the right you will most likely have sea lions with you the entire dive. Deadman's Reef is a long swim from the beach, about ten miles as I recall.
Visibility is usually good here due the distance from shore. Plenty of life to see here.
Shaw's Cove.
Like diving in a maze. Just off the beach to the right is a large crevice filled with mussel shells. At the end of the crevice is a left turn where you'll find lobsters hiding in the large cracks of the rock walls. Make your way through the maze for a nice experience of all that Laguna has to offer. Eels, nudis, sponges, seastars and gorgonian fans cover the walls in places. You can make your way to Seal Rock cove to the right, cut through the left to get back into Shaw's Cove or go out to the end of the reef and swim back along the outside of the reef.
Divers' Cove/Boat Canyon.
If you get here early enough you can find free parking, otherwise plan on bringing plenty of quarters. On the weekends you will find lots of classes before noon, as this is an easy dive. The best diving is on the large reef between the two coves, directly in front of the apartments. Head to the outside of the reef and you will find walls, cracks and holes filled with fish, eels, octopus and lobster. There is a restroom above the beach between Divers' Cove and Picnic Beach. There are several smaller reefs here offshore. A shower is available at the bottom of the paved trail. Picnic tables, barbeque pits and a nice grassy area sits above the beach.
For more info, check out these links;
http://www.geocities.com/sandeaters/sites/sites.htm
http://shorediving.com/Earth/USA_West/CalM/index.htm
