Mexico (Western) Scuba Diving
Including the Sea of Cortez, Baja, Isla Socorro,
Cabo Pulmo, Ixtapa, La Paz, Puerto Vallarta

An Undercurrent Insider Report on Mexico (Western) Diving
The Consumer Newsletter for Serious Divers Since 1975

Overview of Mexico (Western)

The sea mounts of the Sea of Cortez have sea lions and occasional schooling hammerheads, though fi shing continues to wipe out the big fi sh. Still, there's good diving from Cabo Pulmo to San Lucas and even farther north operators are getting to the seamounts. In winter and spring water temperatures can drop to the low 60s. Visibility is lower (25-40 feet), but generally improves to 80 to 100 feet by late summer, when the water warms to the 80s in the Sea of Cortez. From December through May winds kick up the water, which makes diving difficult. Wear a skin or wetsuit for protection from jellyfi sh. Socorro Island has hammerheads and mantas, though it's a long ride from Cabo and there's no guarantee of sharks or good weather. Manta sightings are reliable and they have a reputation for letting divers approach. One can fi nd good accommodations and food at all the dive venues north of Cabo. Farther south, Pacifi c diving is dulled by low visibility.

Mexico (Western) Seasonal Dive Planner

A one-word description of Sea of Cortez diving: variable. Water temperature and visibility varies dramatically. Two divers returning from the Baja only weeks apart can give such different reports that you have a difficult time believing they've been to the same destination.

In the southern part of the Sea of Cortez, the temperature of the upper 30' of water or so remains warm enough year-round (70° to 80s) to support tropicals and several varieties of hard coral. Below that depth, winter and spring water temperatures in the 50s and 60s freeze out the tropicals. From mid-summer through November, water temperature is 80°F or higher for as deep as sport divers would care to go.

During spring and summer, the surface water temperature rises, of course, but the big change is the lowering of the thermocline. This is a complex and uneven process. During a June visit, the thermocline was at 45-50'. Sometimes the change was gradual or of small magnitude, but on one dive we recorded a plunge of 16 degrees between the surface, at 76°, and a thick layer of 60° planktonic green gloom 50 feet down. Later in the season, the water is 80° all the way past 100'. (We've even recorded 84° water in October.)

Another seasonal variable is the plankton concentration. Sometimes the more plankton-rich waters can be observed as distinct layers and masses. Generally, our June visibility was 30-40'. Later in the summer, it's usually 80-100'.

After the first of December, north winds often make diving difficult because of rough seas. Sport diving effectively ceases until May. By spring the thermocline is high and a 1/4" wetsuit is recommended (some sort of protection from jellyfish is recommended year-round). Tropical storms can occur during summer and fall, just as in the Caribbean. On average, they are most likely from mid-September to mid-October. La Paz and its waters tend to be protected from storm swells by a projection of land on the east and by large islands such as Isla Cerralvo.

It's almost always sunny, but during the winter, night air temperatures can drop down into the mid-fifties. Hottest months are August and September. Whale season is December to March.

Mexico (Western) Feature Articles and Reader Reports

Editor's Book Picks for Mexico (Western)
Including the Sea of Cortez, Baja, Isla Socorro,
Cabo Pulmo, Ixtapa, La Paz, Puerto Vallarta

The books below are my favorites about diving in this part of the world All books are available at a significant discount from Amazon.com; just follow the links. -- BD

Sea of Cortez Marine Animals by Daniell W. Gotshall, Daniel Gotshal. It's just the book you'll need to identify critters anywhere along Mexico's Pacific Coast, all the way to Panama. Any other ID book just doesn't cover the creatures here. Dan Gotshall, a marine biologist with 34 years research experience, has more the 250 photos of fish, corals, nudibranchs, lobsters, sea stars and other critters endemic to these waters. For each animal there are tips how to identify and where to spot it. Paper, 110 pages, $20.95

If you're headed south out of San Diego, Fishes of the Tropical Eastern Pacific by Gerald R. Allen, D. Ross Robertson, is the fish guide you need. With 324 photo-packed pages covering 680 species of sharks and sailfish, wrasses and razorfish, pipefish and pearlfish, this is the ultimate ID book for the Baja, Costa Rica, the Galapagos, and the Sea of Cortez. Sponsored by the Smithsonian Institute Drs. Gerald Allen and Ross Robertson took years to produce this definitive volume that describes and comments on the remarkable behavior of these critters. Hardbound, $85.

Coral Reef Animals of the Indo-Pacific
by Terrence M. Gosliner, David W. Behrens, Gary C. Williams.

At last -- a just-published, complete guide to help you identify the uncountable variety of weird critters you'll see on any Indo-Pacific dive, complete with full-color photo of 1,100 species. About Coral Reef Animals of the Indo-Pacific, Chris Newbert says, "This invaluable new book makes identification easy and enjoyable." There are scores of flatworms, nudibranchs galore, bumblebee shrimp, painted crayfish, pompom crabs, side-gilled sea slugs, and endless corals. Marine biologists Terry Gosliner, David Behrens, and Gary Williams cover the reefs from the Solomons to Sipadan, from the Maldives to Maui, from Palau to Papua New Guinea. They provide good notes to help you find and identify each critter. Indispensable for any Indo-Pacific trip. Paperback, 8x110, 314 pages, $45.00.

Indo-Pacific Coral Reef Field Guide by Gerald R. Allen, Roger Steene. I was trying to pack light for a change. Surely the Solomon Sea would have good identification books aboard. Not so; the only book on the boat belonged to a fellow passenger. It was one that I had not seen before, the Indo-Pacific Coral Reef Field Guide, by two of the best fish guys around, Gerry Allen and Roger Steene. The problem was this fellow passenger kept it in a plastic baggie most of the trip and I had to beg to see it. Great book, good traveling size, and it covers everything from fish, shells, marine plants, mammals, corals, and invertebrates to sea birds and more. Now I've got my own, and it won't do you any good to beg me to borrow it. This is one of two books that I will not travel to the Pacific without. Good for travel to the Red Sea, East Africa, Seychelles, Mauritius, Maldives, Andaman Sea, Malaysia, Indonesia, Philippines, Australia, Micronesia, Polynesia, and Hawaii, it has 1,800 color illustrations in a 6x8 1/2 paperback format with 378 pages. $39.95.

You might find some other books of interest in our Editor's Book Picks section.