Rocio del Mar, Sea of Cortés, Mexico

Dear Fellow Diver:

We all know about the power of the San Andreas Fault. Several million years ago, its shearing forces created the Gulf of California, a.k.a. the Sea of Cortés. Like the Red Sea, a creation of the Africa's great Rift Valley, the Sea of Cortés is a geologic wonder, filled with endemic animals. Though around a million people live in Baja California, diving the waters of the northern Sea of Cortés feels remote from civilization. While diving around the Midriff Islands in August aboard the Rocio del Mar, I was awestruck by the beautiful desolation.

Rocio del Mar, Spanish for "sea mist," carries 20 divers and almost as many crewmembers. Her captain, the aptly named Rey ("king"), varies the itinerary as dictated by weather and diving conditions, and will change sites if divers express strong wishes. She plies the waters from the southern Socorro Islands in the Pacific to far north in the Sea of Cortés, depending on the season. The diving varies wildly, from pea-soup visibility, cold upwelllings and currents, to warm, clear water, caused by the massive tides and river sediment in the northern Gulf (where the Colorado River deposited silt for millions of years), and currents mixing with the Pacific Ocean farther south. The northern Sea of Cortés trips depart from Puerto Penasco, about an hour drive from the Arizona border town of Lukeville, in the Sonoran Desert, a four-hour drive from Phoenix's airport.

This is a dive trip for the prepared diver. The boat is sturdy and functional, not glamorous. The large galley and crew quarters are on the lower deck; on the next level, the smallish dive deck holds eight double cabins forward; the third deck includes a salon, covered relaxation area and two slightly larger cabins; and the top deck houses the compressors, sun deck and a table where the crew sets up barbeques. Two massive stabilizers swing out from the sides as she enters open water. Cabins are quite small and short on storage (netting or extra shelving and hooks would be helpful) but sport comfortable new memory-foam mattresses. Ensuite bathrooms are basic and also short on amenities (mine had no rack or storage in the shower). While the water is hot, there are never enough towels (each diver is provided one bath towel and one washcloth). I was glad I brought a stack of microfiber utility towels from Costco to augment the supply. Consider bringing a hair dryer and lots of shampoo,because neither is provided. The current is 110 volts, and an 800-watt dryer did not seem to tax the system.

Bring plenty of layering options for the water. Rocio del Mar usually offers four dives per day, and waters can be cold for all but a few months. It's not so much thermoclines as upwellings and mixing of warm and cold waters; you can rarely predict when you will hit a patch of water in the low 60s. While the water warms considerably into November, I was there in early August and wore a 7mm wetsuit with a full polyolefin suit underneath and a fleece hooded vest, often augmented by a 2mm hooded vest and mini-hood from Terrapin Wetsuits. My buddy wore a 5mm with a 3/5 hooded vest and polyolefin suit. Both of us wore gloves and socks under booties to keep chafing minimal. I was never too hot (air temperatures of 98 degrees suit me fine) but a few polar bears seemed okay in lighter suits. Being cold is miserable, and the crew will help you with your gear so the extra weights required don't drive you nuts. You will also need to add weight, not only because you're wearing more rubber than usual, but also because the water is very saline. And bring a focused LED light -- it will help on daytime dives for peering into the rocks, and for the night dives.

The all-Mexican crewmembers speak good English, and though their jobs focus on a certain tasks (food, diving, engineering, etc.), all pitch in as needed. Chef Pancho may be the only one whose job never varies, to the delight of guests. He and his staff never needed more than one reminder of dietary preferences (one diver ate no fish, another needed small portions, one was vegetarian, and another disliked cheese). I preferred the Mexican dishes, like chicken and beef tacos with flour and corn tortillas and a plethora of sides, but the more continental dishes, such as pork chops en croute or pumpkin soup, were also delicious. Every dinner begins with a hot soup and ends with dessert. One timing change that I appreciate is having dessert available after, not before, the night dive.

All the divers aboard my trip were Americans, but books on the boat, and the guest log, told me European divers, especially Germans, are frequent guests. I can see the appeal: One can combine a dive trip with a visit to the Grand Canyon and Las Vegas, both a few hours north of Phoenix. Divers are split into two groups, each with its own panga. Dive times are limited to 60 minutes, 50 for night dives. I often came back with 900 to 1500 psi, but I understood the logic of the restrictions, though the panga drivers seemed to have diver-oriented GPS. Between unpredictable currents and visibility, groups need to stay together for safety. Entries are by backroll from inflatable pangas, and exits are easy because the pangas have ladders long enough even for tall divers. I took off all my gear, handed it up, then climbed up the ladder. Seas can be rough, so abandon your vanity and plop your butt on the inflated edges, then swing your legs over while hanging on tight.

I mentioned a sense of awe, and now that the practicalities are out of the way, let's talk about that. Our first dive was at Piedra del Angel. As one of the largest islands in the Sea of Cortés, Angel de la Guarda is itself a geologic marvel -- 45 miles long, only 10 miles from Baja but separated by a mile-deep trench. The temperature averaged 72 degrees on a rocky bottom alive with invertebrate life and swimming with fish. Gilberto, our divemaster, assessed the needs of the group while my buddy and I took in the bivalves littering the bottom, like garbage outside a clam shack, and the many skates, rays (including small electric ones), eels, octopuses, huge triggerfishes (including the endemic big boy, the finescale trigger, almost the size of a Titan), massive groupers, scorpionfish so cryptic I nearly rested hands on them, sea stars and magnificent angelfishes, like the yellow-tailed King and the yellow-striped Cortés. My logbook notes how rich these waters are with life -- clouds of juveniles, schools of small Mexican barracuda, the occasional seahorse and frogfish -- and all this despite the threats of overfishing looming in this UNESCO-protected area.

Guitarfish were common around Angel de la Guarda, as were giant jawfish, whose faces poking out of the rubble looked like comic-book fish. Some held eggs in their mouths and allowed a close look. On the east side of the island, Punta Diabla featured a cut-through that framed the blue water beyond with lush soft corals, as bump-headed Mexican hogfish cut back and forth. Grand vistas gave way to sandy-bottomed comedy as orange pikeblennies engaged in bold nuptial displays. Many sites included meadows of bushy black corals in neon yellow, a far cry from the familiar evergreen black corals.

Further south on Angel de la Guarda, and on the smaller island of San Pedro di Martir, are colonies of sea lions. One reason I love diving is that it allows you to play like a kid, and as playmates go, sea lions function as 700-pound marine mammal toddlers. They came up to my mask, snorted bubbles and enjoyed games like spinning and chasing tails as much as my nieces and nephews do. The waters of San Pedro di Martir were the warmest and clearest of the trip, between 74 and 84 degrees, with rocky bottoms and, as my log attests, "lots of big ass fish."

Being with sea lions highlighted a distinction my buddy and I have long contemplated: divers with cameras. I no longer call them "photographers," because that implies mastery and professionalism. With the advent of digital, anyone can use a camera underwater, and the nicest folks on the boat become Mr. Hydes underwater when holding a camera. Because conditions mandated diving in a group, the aggregation and sense of entitlement of the camera holders was magnified every time the divemaster pointed out something. By "aggregation," I mean clusterf***s, traffic pileups that had me cowering on the bottom, covering my head to keep from being kicked. While I used the camera in my head and cavorted with sea lions, most other divers with cameras fought for position and viewed the 360-degree world around them through viewfinders. They missed the joy of play, turning their dives into hunts for usually poor images and inadvertently pissing off their fellow divers with their mono-focused diving for pictures. On most liveaboards trips, usually someone is a real jerk. This group was unusually pleasant, a mix of active and retired professionals, teachers, healthcare workers and rocket scientists, all eager to get along. Yet underwater, these nice people morphed into monomaniacal digital monsters. Note to self: Can liveaboards offer camera-free trips that are actually about diving?

Rant over; time to talk about food and service. Rocio del Mar is unusual in not charging for alcohol, though like every good dive operation, the rule is your first drink signals your last dive. In addition to very quaffable beers and wine, they offer frozen margaritas and mixed drinks, as well as plenty of soft drinks and cold hibiscus tea. Though I retired early, some divers stayed up watching movies from the library in the salon. The daily menu was posted at the hot breakfast (which came after continental breakfast at 6 a.m. before the first dive) and combined vegetarian, American, and Mexican offerings. Meals are served plated and attractively garnished, and special diets and requests are accommodated without fuss. Every member of the crew joins in serving meals, and during my week, they hosted two barbeque dinners on the top deck as well. Three tables in the downstairs dining room accommodate all divers, so you necessarily get to know everyone while at table. When barbeque dinners are served on the top deck, tables are six-person picnicstyle. The lighting in the dining area is a tad harsh rather than atmospheric.

The level of service makes up for small cabins and few towels. Prefer to gear up on the panga rather than the dive deck? No problem. Want a diet soft drink? A deck towel? Forgot your mask? No problemo. I saw Captain Rey helping out on the dive deck, and divemasters serving meals. I have heard that the boat's owners, Dora and Lolo Sandoval, have worked hard to create a warm, family atmosphere amongst the crew, including firing folks who developed attitudes. The crew's attitude made it easy to dig into my wallet at the trip's end for a good tip (and this trip is not cheap, coming in around $350 per day).

The last day of my trip was devoted to snorkeling with whale sharks in the national park around the Bahia de los Angeles, about 12 hours steam south of Puerto Penasco in the northern Sea. The waters are murky, the laws strict (no more than four snorkelers per animal) but darned if there weren't whale sharks for everyone. In a lucky fluke, I spent 10 minutes alone with one beast swimming placidly with an open mouth and festooned with remoras. The park fee of $28 is good for a year at all Mexican national parks, so keep your card.

I would definitely take this trip again, and indeed, I fantasize about the boat's itinerary from the far north to far south. It 's not plush, conditions could suck, and you can get very cold if unprepared. But it's so unusual here, so remote and so filled with life and variation, one trip to the Sea of Cortés must beget more, if only to immerse yourself in its many personalities.

-- J.D.

Divers Compass: This trip embarked from the Phoenix airport, and the transfer to Puerto Penasco ("Rocky Point") is by vans run by "Head Out to Rocky Point," sufficiently comfortable for the four-hour ride; owners Mike and Lynette went out of their way to retrieve a phone I'd left on a van on the way back ( www.headouttorockypoint.com ). . . The drive down includes a rest stop where you can buy food and drink . . . There are no land excursions offered on this itinerary, but you can extend your stay at resorts in Puerto Penasco . . . Nitrox is available for $120 per diver for the week; on this trip, all save two divers used it . . . All equipment is available to rent, including wetsuits, though to get exactly what you need, alert management before you arrive . . . Website: www.rociodelmarliveaboard.com