Some of my favorite diving along the California coast in on (or rather under) the oil platforms. There are plenty of them here, but only 3 are accessible to hobby divers. A couple years ago Platform Grace near Ventura was open as well. I never got the full story on what exactly happened, but they closed it after some legal issues. Best I know is that some diver got into trouble and then sued the rig operator. That now leaves Platforms Eureka, Ellen and Elly as the only options.
All the rigs around the Santa Barbara Channel are platforms as they go all the way down to the ocean floor rather than float. They look essentially like a huge steel tower. What makes the rigs so special is that they all sit in deep water (720 ft in case of Eureka). The legs are the only thing available for life to grow on and it becomes a beautiful artificial reef. The colors are stunning and if you are really lucky you get to see some of the large animals that call the channel home. I got to see a Mola Mola many years back, but I have heard of gray whales stopping by on rare occasion.
I forgot one reason to go dive the oil rigs: Scallops! You can easily get a dozen or two large scallops on each dive. Those are nice 1-2 in sized ones. And after eating a truly fresh scallop you will never go back to a store bought one. A couple divers in our group were so generous with their haul that they donated a couple to prepare a fresh scallop ceviche for the group. It was awesome!
The 3 rigs are still very much in operation and just a tourist attraction. That means that boats move about, pumps are active and things can and do fall down on occasion. Diving is also more challenging because of the depth. For all intense and purposes there is no seafloor. If you see it, enjoy as you will be dead pretty soon. The open ocean provides for great life, but also for great currents. And finally, you are in what is really a steel cage and that makes the compass all but useless. Visibility is hit or miss. I had dives with crystal clear water and 100+ ft and pea soup dives with less than 20 ft.
The first dive today was on the wreck of the Olympic. No photos as I forgot to put a memory card in my camera and only noticed at 90 ft depth. Rookie mistake. Dive #2 was on platform Eureka. No current, but also not much in terms of visibility in the first 80 ft. Below the thermocline the water cleared up considerably for a nice and relaxing dive. For the last dive of the day we went to platform Ellen. I like it better than Elly because it has a lot more pipes running down and thus a lot more growth. There have been better conditions on other dives, just look for older posts here. This was still a great day under the beautiful California waters.
As I mentioned before it was pretty green today. This makes taking nice photos that much more difficult. Especially when you try to take wide angles. I could put a macro lens on, but I already have so many of those. So instead I tried to go more for the monochrome look. The B&W are altered, but the green and blue filters were the actual water. That is what it was.