The San Diego Chamber of Commerce couldn't dig up stronger allies than these people. Almost to a man, these people — the diving fanatics in town — claim that there is no finer place in the world — for scuba diving. Not Hawaii with its jade-colored water and brightly colored fish of Hanauma Bay. not the Bermudas with their reefs. And of course not Los Angeles, whose sewage has destroyed much of its diving opportunities.

The reason is San Diego's kelp beds. "Where else can you walk out 50 yards into the water and see the sea anemones, rockfish, sheepshead, lingcod, black seabass, garibaldi, and shellfish? Why, our kelp beds are like tropical rainforests. You can prowl around for hours," confided an anonymous scuba fanatic who kept me on the phone for an hour and a half. "Sure, you may find more brightly colored fish if you snorkel on the reefs or Hawaii, but once you're down deeper, there aren't any colors on the fish anyway. The red color, for example, disappears about 30 feet down. Your underwater photographer will tell you about San Diego. He gets more variety here than anyone else."

One thing that must be cleared up at the beginning of any diving discussion is the difference between a Scuba (Self Contained Underwater Breathing Apparatus) diver and a skin diver (no breathing apparatus). The confusion arises because the original deep drivers were always "skin" until the breathing tanks were invented and now, even the phone book refuses to call scuba divers anything but "skin divers."

One difference between the two is that scuba divers wear wet suits more regularly. "You need a wet suit year round if you go below 30 feet. The sun only warms up the water's surface. Once you go down below the termocline, you get all kinds of cold currents," said the phone caller.

And that is one of the reasons the most hardcore scuba divers are advocates of water diving . Through the water's surface is warmest during the months of August and September in San Diego, the water clears up in October and the best months for digging are October and November. The first of October the coming of the cold water kills the plankton, and the visibility almost doubles. "It goes from 50 feet to about 80 or 90 feet," explains Bob Pontius of the Diving Unlimited shop. "There are more varieties of fish in the winter. The lobster come up from deeper eater and the hunting season starts. 'Course hunting isn't as good as it used to be. I grew up in Carlsbad, and I remember when you could go out and get a 15-pound bull lobster; now you're lucky if you can get a three-pound one. The commercial divers are taking a lot — about 10 times as much as the sport diver. Of course, they claim they have to make a living on their catch."

What are some of the places divers can go in San Diego? Any of the shops can recommend diving sports, but a few deserve special attention here:

1) North County. The kelp beds and reefs are generally offshore 500 to 1000 yards and usually you have to be a strong swimmer or have a boat to reach the good diving in unexhausted shape. Though the visibility is generally poor in this area, especially compared to La Jolla, the small number of divers means there is better hunting for those who do dive there, especially for lobster and abalone. Though the clearest water is at Swami's — the famous surfing beach near the Self-Realization Institute in Encinitas (access is from a dirt path just north of the Sea Cliff Park campgrounds) — the reefs at Tide County Park (between Cardiff and Solana Beach, at the foot of Solana Vista Road), Cardiff State Beach (San Elijo State Park), and Moonlight State Beach (turn off Highway 101 at Encinitas Boulevard or at E Street in Encinitas) provide the best combination of sea life variety and good visibility available.

2) La Jolla. When the Spanish chartered San Diego, the 3000-acre area of water, extending from Goldfish Point (or at the La Jolla Caves) to Del Mar, were deeded to the city. This area is now the San Diego underwater Park, one of the few (if not the only) city park of its kind. Within the park is teh 520-acre Ecological Reserve, which goes from Goldfish Point to the Scripps Institute Pier. Nothing can be removed from within the Ecological Reserve.

There are two very deep canyons within the park. Scripps Canyon, one of whose three branches begins a half mile north of Scripps Pier, comes within 200 yards of shore. Parts of the canyon are extremely narrow — at the 150-foot depth in the South branch, a diver can touch either wall — and parts of the canyon are extremely steep — the eastern wall of the North branch is a sheer dip from 100 to 300 feet. Though there isn't a lot of sea life variety, the water is usually clear. La Jolla Canyon, right off Kellogg Park at La Jolla Shores, is frequently used by diving classes for checkout dives. Almost a thousand yards from shore, the canyon rim is about 50 feet below the surface of the water. The visibility can be 40 feet if there is sufficient upwelling from the canyon but bad surf condition can make things pretty cloudy. The big sea life attraction in La Jolla Canyon is the large squid spawn in the late fall.

The other La Jolla beaches also have a good variety of reef formations and wildlife. Goldfish Point Loma has shallow reefs, lots of marine life, and a large forest of ribbon kelp. The cove, generally the most popular with new divers, has a scenic rocky bottom. Bommer Beach, just off the Scripps Park shuffleboard courts, is famous for its grouper — which were almost extinguished several years ago — and its dangerous rip tides. Casa Cove, just south of the Coast Boulevard lifeguard headquarters, is excellent for snorkeling.

3) Point Loma Kelp Beds. Since the beds lie off restricted federal property and since they are generally at least a half mile out, they are best reached by boat. The kelp beds provide some of the most scenic diving in the world. The kelp hangs over a large reef whose ledges are covered with sponges and sea anemones. Withing the kelp itself teem lots of rockfish, kelp bass, sheepshead, and sea bass. The visibility, which can go as high as 50 feet, provides excellent conditions for photography. Besides the kelp itself, the distinctive landmarks in the area are the Loma Sea Cliff, which parallels Point Loma on the outer edge of the kelp beds and is composed of ridges and sand channels, and New Hope Rock which is almost exactly two miles south of the Ocean Beach Pier.

4) Other diving areas. The Tijuana Sloughs area, approached from Imperial beach, can be good for halibut and lobster hunting, but usually has poor visibility and can have dangerous riptides. Along Sunset Cliffs Boulevard (Pescadero Point, No Surf Beach, Lascombs Point, and Rockpile) there can be good hunting, especially for shellfish, and some photography, especially for close-up work. But the entry along the rocky area can be tricky. The Mission Beach Jetty has good hunting and snorkeling, but the mussels along the rocks can be hazardous and diving along the inside of the jetty is illegal.

Unfortunately, except for the casual snorkeler, diving is not a poor man's sport. One can get a used wet suit for as little as 40 or 50 dollars through classified ads or garage sales of from a Navy UDT or SEAL buddy. Once can buy a new "box" suit for $80 to $120. But for someone who is interest in diving or spending much time below the thermocline, a custom wet suit ($160 to $300) is probably the only thing that will keep him warm for long periods of time.

One fortunate thing for the diving consumer is that there is fierce competition between the local diving shops here. New England divers, for example, began to offer those who bought its tanks a lifetime supply of free air. To top them, Diving Unlimited has begun to offer free air to anyone who walks in the store. Fortunately, too, most of the diving shops are very safety-conscious, the bad P.R. of a diving death is understandably not too good for business. And most of them provide diving instructions.