A great spot if the surf isn't too big. Parking can be downright unpleasant, especially in summer (when you should get there at 7:00 AM if you want a reasonable parking spot).
The Cove has shallow, rock reefs with a lot of fish and other living creatures. You're likely to (sometimes) get more unusual, awe-inspiring things at the Shores than at the Cove, but the Cove always has a lot of life (it just doesn't vary as much as the Shores). The Cove also has kelp beds on the outside.
The Cove is in a marine protected area. Please do not remove anything except floating plastic garbage (e.g., plastic wrappers, small plastic bags). Please do not disturb or kill any living things or remove/damage any archeological artifacts you might find.
There are a number of different directions you can go once you get in the water at the Cove, to fairly different environments.
10–20' deep rock reefs. Lots of life. Several types of schooling fish, garibaldi, horn sharks, sheep crabs, kelp crabs, lobster, kelp bass, sheepshead, giant kelpfish. Keep your eyes open for bat rays and the occasional non-horn shark. Nice diving if not so much swell and not so much detritus washed into the Cove.
This is a bit of a swim. Get in the water at the Cove and swim out to the first yellow buoy (straight out and a bit to the left). Don't confuse it with any of the white swim buoys. There are three yellow buoys (A, B, C) in a line running north, you want the closest one. Beware of kelp patties on the surface swim out. Drop down at Buoy A, in 40 feet of water or so. You will be in the middle of a large area of piled up rocks, thus the name. It's a good-sized rock reef system out past all the other in-close reef, surrounded by sand and kelp. You'll find much the same life as in close, but are less susceptible to swell and have the combination of rock reef and kelp. You may also get a few more pelagic strangers than you'll find in close (examples of things seen here include mola mola, blue sharks, and grey whales). The kelp in the general are of Buoy A is where giant sea bass, soupfin sharks and sevengill sharks are sometimes seen. When you reach your air turnaround time, take a heading of about 200 degrees and work your way back to the Cove.
Exactly where the kelp beds are at La Jolla Cove varied from year to year with the ocean water temperature and from big storms, but generally the kelp forest is wide out and around the left of the Cove and tapers down coming east past Buoy A. There's generally still pretty good giant kelp in the area of the Rockpile and a bit east (but not a lot inshore of Buoy A), which then converts to feather boa and understory kelp as you continue east. As you get much north / northeast of Buoy A, the kelp ends and you have sandy slope which eventually turns into the submarine canyon.
Only do this dive under very calm conditions. Boomer is named Boomer because of the sound the waves make breaking on the point by the Shuffleboard Club at the Cove. In close to the point is very shallow and you don't want to be there with any swell. On calm days, you'll get to explore some great rock reefs with a lot of life. Look in and under things for moray eels.
Not far offshore around to the right is as described above for the Cove, but in at the cliff are a number of caves, with great rock reefs in very shallow water right in front of them. You'll find a lot of life. You can enter several of the caves, including one with an underwater entry and the passthrough under The Clam. Do this only on calm days and higher tide... even better with someone who's done it before.
Of these four named rocky pinnacles grouped together offshore of Point La Jolla, the best known is Quast Rock, which sits way out northwest past Boomer in about 65 feet of water. Generally, it's a boat dive site—unless you're feeling extraordinarily ambitious on your surface swim. There are several known "rocks" (stubby pinnacles) out there—Quast Rock, T Rock, Anchor Rock and God's Rock—and you will frequently see people in small skiffs or kayaks out fishing there.
Here are the published Seadeucer's line-ups for Quast Rock:
All of these sites are large rock outcroppings right on the edge between the rocky reef of La Jolla and the sand falling away offshore at depths of 65—75 feet. Relief on these outcroppings varies from 5 feet to probably 20 feet. There are lots of interesting rock fingers, small caverns, holes, etc. This is also generally the edge of the kelp forest, so you not only have great rocky outcroppings to explore, but then you've got a built in, interesting ascent "line"... the kelp.
Quast Rock features a good size cavern on the side facing the sand, with a hole through the top of that cavern up to the large rock "plate" above.
T Rock features a quite large T-shaped rock on the inside, left corner (when facing from the sand side). This T-shaped rock is probably 10 feet tall and about that wide. At the outside, right corner you'll find a smaller mushroom shaped rock.
Anchor Rock had quite a few outcroppings, fingers, holes, and other interesting formations, including the massive formation on the far left (when facing from the sand side) which presumably gives the site its name: the massive rock there (probably 20 feet tall) looks very much like a classic anchor symbol.
God's Rock, like Quast Rock, is a little smaller than T Rock and Anchor Rock, but again provides some great rock formations to explore.
GPS Coordinates are as follows:
Here are photos of the Seadeucer's Quast Rock line-ups:
Finally, to give you an idea of how close these dive sites are, here are these sites on a bathymetry map from SIO: