Revillagigedo Islands, Mexico

I just returned from the Islas de Revillagigedo, off the Pacific coast of Mexico. Located two hundred twenty miles south of Cabo San Lucas at the tip of the Baja Peninsula and more than three hundred fifty miles from the Mexican mainland, the area consists of four volcanic islands; Socorro Island, San Benedicto Island, Clarion Island and Roca Partida.

Due to their isolation from the mainland, these islands are home to a variety of endemic plant and animal species. Below the surface of the surrounding Pacific Ocean, the islands are renowned for their prolific marine life, including giant mantra rays, many shark species, big pelagic fish such as yellowfin tuna and wahoo, and dolphins and humpback whales.

In 1994, the Mexican government established the Revillagigedo Islands “biosphere reserve” to protect this unique ecosystem. Accordingly, commercial and sport fishing boats are now prohibited within twelve miles of the islands and visitors are not allowed to set foot upon the islands, which are uninhabited with the exception of a small Mexican military facility on Socorro Island that serves to enforce the reserve’s regulations. Even with this small military presence, the remoteness of the islands makes enforcement difficult. There have been several well publicized incidents in which long-line fishing boats were “caught in the act” inside the reserve’s twelve mile limit. So dive boats, like the one I was on, play a valuable role in protecting this unique resource by notifying the military authorities when fishing boats are in the area.

In some respects, traveling to the Revillagigedo Islands is pretty easy. It takes only a short four-hour flight to get from the east coast to Cabo San Lucas (although there are no direct flights from the Washington, D.C. area). But from the marina in Cabo San Lucas it takes about twenty four hours by boat to get to the nearest island, San Benedicto. This is not always an easy crossing; the ocean can be rough. We had a comfortable trip south to San Benedicto, but faced four to eight-foot swells on the return trip north.

Diving at the Revillagigedo Islands is a unique experience. Unlike my normal diving destination, the underwater scenery here is generally unattractive, consisting of grey rock formations with only a small amount of hard coral, and the marine life lacks biological diversity. But what is lacking in underwater scenery and diversity is offset by large marine animals and clear, blue water. My previous trip to the Revillagigedo Islands was in the fall of 1997 and I still have vivid memories of being submerged in the stunning blue water, swimming with the giant mantas, and being buzzed by hundreds of sharks of different species at Roca Partida. I’ve wanted to return ever since, mostly for another opportunity to photograph the graceful mantas.

The diving here isn’t always easy. The currents can be very strong, and on nearly every dive a strong surge is felt, often to as deep as eighty feet or more, so it’s not easy to hide from it. The water temperatures are pleasant; normal January temperatures are in the mid-70° F range, but it was warmer this year, with temperatures routinely between 77° F and 79° F. As I remembered from my earlier trip, the water was very blue and visibility was often in excess of 150 feet.

During this trip, I was able to dive at San Benedicto Island, Socorro Island and Roca Partida. As a whole, the diving was exceptional. Of course, there were some slow dives; perhaps the fish were napping, but most of the time there was so much going on beneath the water’s surface that it was difficult to decide what to watch. Scorpionfish rested on the rocks, while large green moray eels poked their heads from crevasses or could be seen swimming to a new hiding place. Lobsters were commonplace, as were octopuses; I even saw two octopuses mating at a seamount called “the Boiler” at San Benedicto Island. And there were plenty of schooling fish; wahoo, tuna and jacks. Every place the boat was anchored, we saw sharks and the giant mantas, often before entering the water.

As their name suggests, giant mantas are really big, growing to a maximum width of twenty two feet (and possibly more) and weighing as much as 3,100 pounds. Giant mantas are related to sharks, since like sharks, they have skeletons made of cartilage.

Despite their massive size, giant mantas are harmless to people. They are gigantic filter-feeders, straining the water for plankton and small fishes through their very wide, rectangular mouths. Cephalic lobes, or fins, on the sides of their head are unfurled when the animals are feeding, funneling water and food into their “super-sized” mouths.

Giant mantas generally inhabit tropical sea waters around the globe, usually near shore in the vicinity of coral reefs and rocky outcrops. They are most often encountered near the surface of the water, although recent research indicates that they may dive to very deep water at night. They are solitary animals that do not form schools, but they may aggregate in waters with rich feeding opportunities.

At San Benedicto, at the Boiler, I enjoyed my first brief encounter with a friendly manta. I was nearing the end of my dive after photographing the mating octopus. As I approached my safety stop depth of twenty feet, I turned around and looked away from the seamount to see a black giant manta swimming past. I swam out to see how the manta would react and it approached. After taking a couple of photographs, I turned around to swim back to the seamount. To my astonishment the manta followed me!

With my dive computer loudly beeping that I was running low on air, I stayed with the manta a short time longer, until finally I ascended, inflated my buoyancy compensator and signaled to the boat to send someone to pick me up. Looking around, I was again astounded to see the manta at the surface with me, its dorsal fin above water, circling to keep me company until the boat arrived.

The next day we were at Roca Partida, the smallest and most isolated of the Revillagigedo Islands. A guano covered white rock so small that a diver can easily swim around it during a single dive, Roca Partida is separated from the nearest land by eighty miles. Rising alone from the deep blue, Roca Partida is a magnet for marine life, including giant mantas.

I spent two days at Roca Partida diving with the twenty foot wide giant mantas in beautiful blue water with over 150-foot visibility. Here, I watched as many as three giant mantas at once. They would swim toward me, stop and hover in the water column until I would swim under them and rub them on their bellies. The mantas seemed to recognize me, seeking me out among the other divers, posing for photographs and pleading to have their undersides rubbed. I gladly paid the mantas their modeling fees!

On the final day of the trip, we returned to a spot called “The Canyon” at San Benedicto Island. To avoid other divers and their bubbles in my photographs, throughout the day I entered the water when the other divers were back on the boat. On two successive dives, two mantas came to visit, circling me, one following the other, to pose for my camera and have their bellies rubbed. The mantas so insisted that I rub their undersides that my hands became raw and began to bleed from their sandpaper-like skin!

In addition to the giant mantas, I saw a lot of sharks here, at least relative to other diving locations. There were white-tip reef sharks, silky sharks, Galapagos sharks, silvertip sharks, scalloped hammerhead sharks, a great hammerhead shark and even a tiger shark. But missing were the hundreds of sharks I remembered at Roca Partida from my trip there only seven years ago. Why? Was it because the water was unseasonable warm and the sharks were in deeper, cooler water? Or was it because the shark population here is being adversely affected by over-fishing, like other places in the world? I hope for the former, but I fear the latter; that even in these remote, isolated, uninhabited and protected islands, the sharks are rapidly being destroyed by the world’s floating fishing factories.