I love diving Catalina Island. It is one of my favorite places in the whole world to dive. But after having dived Catalina thousands of times, it can seem at times to get a little old; however, there are excellent dive sites that are rarely visited. Why theses sites are rarely visited is quite simple: they are definitely advanced sites. The reasons are twofold — strong currents and depths. While not exactly “secret,” these charter boats will sometimes hesitate on taking divers here unless firmly confident of their passengers’ abilities. 

California Diving News
LITTLE FARNSWORTH
Of the three sites I will discuss here, this is probably the most often visited. While not as spectacular as its namesake on the backside of Catalina, this rocky spire is definitely worth a visit. Rising from a sand bottom at 130 feet this pinnacle tops out a 60 feet. Most of the diving is done in the 80 to 100 foot range. The site is small enough that the main pinnacle can be given a cursory overview in one dive.
Bring a light and the immense amount of color will slam you in the face. There are yellow walls blanketed with tiny zoanthid anemones. One particular species of zoanthid specializes in overtaking gorgonian branches to create huge fans of hairy bright yellow bushes.
Gorgonians, by the way, are also prolific. Golden and red gorgonian also add to the color explosion. There are sponges and corynactis anemones also covering the rock face like a multifaceted blanket. Threaded in and out dance nudibranchs, blue-banded gobies, and zebra gobies. 
Topping off this color parade are sheephead and garibaldi. While not colorful, but rather impressive by their size, is the giant black sea bass that visit the spot in the late spring through early fall. 
There are other pinnacles nearby. Just to the west and out a bit are a deeper rock and an inshore rock rising from 90 feet. None of these locations are marked by kelp.
Little Farnsworth is just a short distance southeast of Avalon. To locate use depth finder and GPS coordinates GPS N 33°20.027′, W 118°18.458′. Hazards here include boat traffic, fishing line, strong currents and extreme depths.
THE HIGH SPOT
Also known as the Rock Pile, I am surprised another more interesting name has not been assigned to this location. Perhaps it is because it is the most rarely visited of the sites I will mention here. (I have only dived this location from a private boat.) Strong currents plague this site almost constantly. Fishing line is prolific and the underwater topography is not terribly interesting. (The name “Rock Pile” is appropriate.) Two things make this site fun and interesting — lobster and nudibranchs. It is filthy with lobster; ‘nuf said. And of all the sites I have dived on Catalina this one has the most nudibranchs in numbers and variety.
The kelpless reef area is small and peaks out at about 50 feet but most of the diving is in the 60-to 70-foot range. Steep drop-offs on the outer edges of the reef, however, make it possible to get past the sport diving limits quite easily. The location is marked on most charts simply as “6 ½,” just northwest of Bird Rock at N 33.27.286′, W 118.29.409′ but use a depth finder for exact location, otherwise you might find yourself on a deep sand flat. Because of the nearly constant current, open ocean location and heavy boat traffic, always use a trailing current line and buoy, dive flag and emergency dive sausage.
WEST END SECRET SPOT
Let me start by saying that I was first taken to this location by Pam Driver, former skipper of the Encore, now a fishing charter out of San Diego. At the time I was not allowed to GPS the location and I respected that request. So you won’t see a GPS coordinate on this spot in this article. Some dive charter boats will occasionally visit this spot on request.  But others say it does not exist (Maybe this site should be called “Shangri-La”). The best I can tell you is it located off the west end of the island. Even if you had the GPS coordinates you would need a depth finder to locate it precisely as it is a small, steep pinnacle, and there are several additional, less spectacular pinnacles in the area.
The dual point pinnacle peaks out at about 70 feet with a smattering of kelp and a ridge joins the two pinnacles. The steep rock faces bottom out about 110 feet and jumbled boulders ramble downward into the depths. This spot is about as virgin as you can get at Catalina. Fish are prolific with just about every kind of Southern California fish imaginable including big male sheephead, large kelpfish, cabezon and large rockfish of many varieties. You might even see white seabass or a school of yellowtail pass. On one particular dive we saw two molas hanging in the water. On the pinnacle face are beautiful large stands of red gorgonian giving the spot the mystical look of a strange garden wall. 
A nearly constant current, but not too strong, keeps the water very clear. The site, however, is open to prevailing westerly swell and seas. Hazards include losing track of your air consumption due to beauty.
Shearwater TERN