I've dived both sides.
The outer side (west) is a challenge and should only be dived when conditions are really good.
It's really dirty water diving, the vis is usually not good at all and things 4 to 6 feet away disappear onto the murk quickly. There is a lot of surge on the outside that pulls you in and out of the wall. It's a shallow dive, only 10 to 15 feet deep depending on the tide at the base of the rocks at the sand. The boulders that make up the wall are big, some as big as a Mini Cooper and can form some minor caverns at the base.
Every time I've dived it I made sure to do it on an incoming tide. I parked and geared up in the Campbell Cove parking lot then hiked down to the cove beach. From there I waded across the lagoon along the cliff to the west jetty. I climbed over the jetty and crab crawled out a ways along the jetty then jumped in on the outside. I went all the way out, around the corner, and came back in on the inside along the wall with the incoming tide.
A few warnings:
Don't leave the wall at any time! There is a lot of boat traffic in and out between the jetties! Not only that but if you venture off you may not find your way back if you are too close to the end of the jetty. Coming up in open water could prove to be very hazardous with boat traffic. Maintain visual contact with the jetty at all times. Like I said, the surge can be brutal so be carefull not to get sucked in and out of rocks sideways. The trip around the end can be quite a thrill too, you may have to actually pull yourself around due to hard cross currents. Once you're on the inside coming in it gets much more peaceful. The sand changes to a mud bottom so stay off it. Also, don't come up anywhere on the inside unless you're all the way in and right close to the beach. You can tell because you'll be in only about 4 feet of water. Part of the reason is because the jetty out towards the middle and end is guarded by a group of very large male sea lions. They get VERY cranky when a diver pops up a few feet away from them like I did once. I'll never do that again!
Also the coast guard gets equally cranky if they catch anybody diving on the inside of the jetties. They have a station right in the bay and they go by all the time. So when you come up pretend your James Bond or something and be as covert as you can. Pop your head up slow to look around and keep low until the coast is clear then make a break for the beach. The last thing you want is to come up and see a patrol boat with 4 coasties pointing machine guns at you.
And it should go without saying, but under no circumstances do you venture into the center of the channel underwater where all the boat traffic is! Stay on the wall at all times.
There are some big lings in those caves and I saw an angel shark once about six feet long laying in the mud on the trip in. There are a lot of abandoned crab traps all over those jetties. There is also a ton of fishing line so you'll need shears, cutting tools, etc.
If you're into grabbing a load of crabs there are a ton of big rock crabs along that wall, if you're into harvesting.
Before I forget, that area is known for big sharks. There is a seal rookery on the island right off the jetty. Some very large great whites have been spotted repeatedly over the years trolling for snacks around the island and the jetties, so be careful and keep your eyes open. Stay low and by the base of the structure and you should be fine.
Good luck!
