Mexico’s Majestic Megafauna

Socorro and the Revillagigedos

By Eric Hanauer

If you’ve had your fill of tiny critters and are willing to put up with long boat rides, swells and currents in pursuit of Señor Grande in his own territory, the Revillagigedo archipelago is the place to go. You’ll board a boat in Cabo San Lucas and then motor some 200 miles south for 20 hours to reach the first of four islands: San Benedicto. From there it’s another 30 miles to Socorro and 85 to Roca Partida. The westernmost island, Clarion, is an additional 200 miles away and is seldom visited because the diving at the first three is so spectacular.

Map of Mexico and Islands of Guadalupe

All are volcanic mountains that break the surface far offshore, where they attract a bounty of pelagic species. Any diver seeking encounters with legendary big guys such as sharks, manta rays and even whales and whale sharks eventually has to plan a trip there.

At this point you may be thinking, The ocean is a wild place, and no big animal encounters are guaranteed. That’s true, but if you don’t see mantas or dolphins at San Benedicto, hammerheads at Socorro or lots of sharks at Roca Partida, you’re the unluckiest diver on the face of the earth. They won’t all be there, but it’s virtually assured that some of them will. If the timing is right and you are fortunate, humpback whales and whale sharks may be added to the mix. Even if you don’t actually see a humpback, they often provide the soundtrack for the area’s underwater adventures. I recall filming mantas at The Boiler while being serenaded by humpbacks, actually feeling the whales’ songs in my chest. We didn’t see them on those occasions, but the sound was magical.

The Revillagigedos (rev EE uh hee HAY dose) are sometimes referred to as Mexico’s Galapagos. Underwater, the comparison rings true. Both areas are protected biospheres and part of the Panamic region, and most of the indigenous marine life is identical. But don’t expect land hikes. Even if they were allowed, they would require technical climbing gear for scaling the sheer, barren volcanic cliffs. But some critters will come to you; boobies often hitch rides on the boats for trips between islands.

Map of pretty island at sunset

San Benedicto

San Benedicto is home to mantas renowned for their friendliness. The Boiler, a pinnacle that almost reaches the surface, is a cleaning station where the giant elasmobranchs are serviced by wrasses, jacks and Clarion angelfishes. Every manta at The Boiler has two remoras attached — never fewer, never more. Nobody I‘ve spoken to has a good explanation for it. I’ve had up to a dozen mantas all to myself there, all posing for photographs much more cooperatively than most human models. I’ve been able to dedicate entire dives just to manta sunburst silhouettes or closeups of their faces. On other occasions mantas have followed me back to the boat after I ran low on air. Anthropomorphism be damned; I felt like I’d made some new friends.

Aerial view of a foggy island

In the past few years a school of dolphins has made The Boiler its home. Unlike their brethren that rocket past us, these local dolphins seem to swim in slow motion, as if performing for our benefit. A pod of about 20 calmly gathered and cavorted right in front of us for about 10 minutes. No feeding or baiting was going on; these were natural behaviors. The animals are habituated to divers’ nonthreatening presence, and they rewarded us by being themselves.


Socorro is the only inhabited island in the chain. Gringos usually use the name Socorro to refer to the entire archipelago because our tongues and spellcheckers stumble over Revillagigedos. Socorro is home to a Mexican Navy base, where every boat is required to stop at one point during its journey so documents can be checked. There are several good dive sites at Socorro, and it’s one of the best places to encounter schooling hammerheads.

School of silver fish swim by the camera

Roca Partida

The crown jewel of the archipelago is Roca Partida. Calling it an island is overkill; on the surface it’s little more than a pair of guano-covered rocks. But underwater the rocks’ sheer walls fall off into blue infinity. Because it’s the tallest structure for 70 miles, it’s a magnet for marine life. Huge schools of jacks flow through the water column, whitetip sharks congregate in caverns, and morays peer from crevices. At 100 feet you can look up and see the mountain peaks above the water’s surface. Most of all, though, it’s the expectation of the unexpected that makes Roca Partida special. On many dives over the years I’ve encountered dolphins as well as silky, Galapagos, hammerhead and whale sharks, and I’ve spent two unforgettable mornings there with a family of humpback whales.

Moray eel pokes head out of crevice to say hello!

The last time I visited, we were lucky just to be at Roca Partida. It had been a rough crossing — more than 20 hours in big swells — to get to San Benedicto. The water was choppy, the visibility marginal, and there wasn’t a single manta. But overnight the weather gods turned friendly, and when we arrived at Roca Partida the ocean was a lake. Visibility was a crystalline 200 feet. Throughout our dives we heard the songs of humpback whales, which was wonderful but after a while started to feel like a big tease.

Then suddenly, there they were. At first all I saw were dark shadows. As I got to 50 feet the shadows morphed into a one-ton calf resting underneath its mother’s chin while an escort hovered in the background. I maintained a respectful distance of about 20 feet to avoid disturbing them (and to fit them perfectly into my viewfinder). Slowly the calf emerged, headed right toward me and did a pirouette as it swam to the surface for a breath. As the mother followed, the calf gently placed a fin on her back. The three whales swam a short distance, dived to 60 feet and parked again. Every five minutes the newborn would ascend once more to breathe. This went on for two mornings, allowing me to shoot both stills and video.

Nothing is guaranteed in nature. But just this once, everything came together. That’s the magic of the Revillagigedos. You know something big and exciting is down there waiting for you, but you’re never quite sure what or when.

Momma humpback whale with baby

Being the Baitball in Isla Mujeres

By Shawn Heinrichs

Isla Mujeres is situated off the northeastern coast of Mexico’s Yucatan Peninsula, just a 20-minute ferry ride from Cancun. Despite its proximity to this bustling tourist hub, however, the sea surrounding the island is famous for its abundant game fish, whale sharks, manta rays and various other marine life. Possibly even more than its whale sharks, the huge schools of sailfish chasing shoals of sardines set Isla Mujeres apart.

Four years ago I made my first trip to Isla Mujeres seeking encounters with the elusive sailfish. In more than 20 years of diving I had never seen a sailfish underwater. In one moment, Isla Mujeres changed all that for me, and over the following four seasons I learned how to become one with the baitball.

Anatomy of a Baitball

Understanding the dynamics of a baitball is essential to creating extended encounters and capturing epic images of the magnificent fish in action. Seasons, weather, currents, light, predators and prey are key variables in a complex equation, and when they converge the result is nothing short of spectacular.

In January, February and March, winter storms in the northern Gulf of Mexico drive nutrient-rich waters south over the shallow continental shelf that stretches from the coast of the northern Yucatan. Massive schools of sardines follow the currents, and, in turn, schools of sailfish follow the sardines. When the prevailing winds shift back to the southeast, they push clear-blue water from the Caribbean Sea up and over the rich green waters, creating the perfect conditions for an epic baitball.

Greatly outnumbered by the massive horde of sardines pouring across the seafloor, the sailfish isolate a group of sardines from the rest, forming a smaller and more manageable baitball. The clash intensifies as the sailfish launch an assault on the baitfish. Working as a unit, they come from below and drive the sardines up toward the surface. The regiment of sailfish vigilantly guards the perimeter to maintain the tightly packed sardine ball. Other sailfish swim below to prevent the sardines from making a dash back to the safety of the large shoal below. What follows next is one of the most exhilarating displays of cooperative hunting found anywhere.

The sardines know they are trapped and make a frantic dash to escape. In unison, the sailfish guarding the perimeter throw up their sails to block the approaching ball. Thwarted, the ball glances off and dives down toward waiting sailfish that set upon them with a fury, ripping through the ball with sharp, thrashing bills. Scales shower down as the sardines frantically race back toward the surface. The sailfish now have the advantage, and with the ball under control the hunt begins in earnest.

Two swordfish debate eating a floating baitball

Moments before it strikes, a sailfish hoists its sail while flashing brilliant colors down the length of its body. This display may be a prestrike warning to the other sailfish, or it’s meant to distract the prey. An instant later the sailfish launches upward, racing into the wall of baitfish and swatting the silvery fish with its deadly sharp bill. Scales fly, and injured sardines break from the safety of the ball. Before they realize their mistake, the sardines are snatched up into the mouths of the ravenous sailfish.

The surface presents other hazards to the ill-fated sardines. Hungry frigate birds swoop in and snatch at the baitfish as they pop to the surface. Pelicans join the action, plunging in and scooping up mouthfuls of the fish. The assault continues, and hapless sardines are ripped apart from above, below and all sides. One by one, exhausted and injured, the baitfish fall to the sharp bills of the sailfish.

Being the Baitball

The battle between sailfish and sardines plays out again and again as bands of sailfish savage the weary baitfish. When humans enter the equation, however, the dynamic shifts of the hunt are all too often disrupted. Through trial, error and countless hours in the water with these animals, I have learned some important lessons about how to get close to the action without disrupting it.

The chase. Chasing marine life is generally frowned upon, as it disturbs the animals and results in suboptimal encounters. But with sailfish you have no choice; the baitball is constantly on the run, with the school of sailfish in relentless pursuit. When you first drop in, the sailfish appear to view you as a competitor, and both predators and prey run from you. Excellent fitness and bullheaded resolve are essential to swimming down the ball until your presence is accepted.

See the light. The sardines constantly run toward the sunlight because it obscures their profiles from the predators, and having the sun at your back is desirable if you’re taking photos. If you constantly maneuver into position between the sunlight and the sardines, then eventually both predators and prey will yield to your presence, and the frantic chase will slow into a methodical hunt.

Breathing room. With the action contained, the baitfish will often seek shelter under you as protection from the sailfish. Unfortunately this will work, killing the predation and causing the sailfish to retreat. It is critical to back off and give the predators room to strike without interference. Rotating in and out of the action ensures you will achieve extended baitball encounters and capture epic images.

To personally experience the power and intensity of a sailfish baitball is to witness one of greatest struggles for survival in nature. Each winter squadrons of sailfish do battle in the waters surrounding Isla Mujeres. Long days with hours of searching are a prerequisite for finding the action. But persistence and hard work will pay off, and you, too, can become one with the baitball.

Isla Mujeres: Reflections of the Past

By Shawn Heinrichs

As I gazed from the tuna tower, a sparkle on the horizon caught my attention. Training my eyes on the spot, I saw what appeared to be a disturbance on the surface about a mile from our boat. Excited, I shouted down to Captain Rogelio for confirmation. “No, just bonito,” came his reply. We continued the search, and 10 minutes later that disturbance was still in the same position. Bonito move fast and savage their prey in minutes, so I knew something else was out there. Closer investigation was needed, and with guarded excitement we set an intercept course.

All eyes fixed on the horizon as a hush fell over our team. Six months of anticipation had led up to this expedition — one that depended solely on our captain’s intuition and our best guess at timing. A dozen miles off the coast of Mexico’s Isla Mujeres, we had been searching these empty seas for hours and had not found anything. But that changed in an instant as a large fin suddenly appeared and cut across the surface only 50 yards from our boat. Beyond it more fins appeared — five, 10, 50 … hundreds. Our team erupted into cheers — we had found it.

An open-mouth whale shark looks like its singing underwater

Whale sharks were everywhere, feeding on the surface for as far as the eye could see. Like combines harvesting a field, lines of whale sharks with mouths agape plowed back and forth in the water. We could not believe our eyes, and we had no idea how long the feeding would continue. A mad scramble ensued as each of us fumbled for our snorkel gear, snatched our cameras and tumbled into the sea. When the bubbles cleared, what I witnessed was beyond anything I had ever imagined possible.

The whale sharks appeared as dark silhouettes against the deep, blue water in the early morning light, and they were bearing down on me from all directions. Closer and closer they approached until I realized they were not going to stop. These whale sharks were on a mission, and my presence was of no concern. At the last moment I kicked out of the way, just as the huge mouth of a gulping shark filled my viewfinder. There were spots, a dorsal fin and more spots followed by powerful surge from a massive tail that brushed within inches of my mask. I whooped and hollered, but my celebration was premature. In averting this group of whale sharks, I had landed in front of another one coming from behind me. Moments later I felt my back being sucked into a shark’s mouth, and suddenly I was tumbling in its slipstream. A group of whale sharks steamed by, running headlong into another whale-shark train and colliding like a rush-hour pileup. The action continued well into the afternoon until our bodies were spent, our batteries drained and flash cards full. Exhausted and all grins, we headed back to Isla Mujeres to celebrate with cervezas and guacamole.


For the next two days we were the only boat interacting with this gathering of more than 300 whale sharks. But a secret of this magnitude was impossible keep on such a small island. Half a dozen boats packed with excited tourists joined us on day three, and the following day brought another two dozen tourist boats along with film crews and scientists. As the days passed, the number of boats and tourists steadily increased. Overnight, an ecotourism industry had sprung up — one that would transform the island and the livelihood of its community.

Underbelly of a whale shark
The world’s largest known whale-shark aggregation was discovered only a few years ago off Isla Mujeres. The sharks gather each year to feed on the eggs of little tunny.

Four years have passed since we swam with that whale shark aggregation off Isla Mujeres, and the whale sharks continue to return by the hundreds each summer. For how long this been happening, nobody knows for sure, but it is astounding that the greatest whale-shark aggregation ever discovered could go unnoticed until a few years ago, especially considering its proximity to a bustling urban center. Fishermen have become tour guides, and more than 50 day boats now ferry tourists out to swim with the whale sharks. Hotels are full, restaurants are packed, and business is booming. We now know the whale sharks converge on the area to feed on the tiny, clear eggs of little tunny, members of the tuna family, which spawn in huge numbers along the continental shelf. Older fishermen recall spotting large groups of whale sharks as long ago as they can remember, but back then nobody paid much attention to sharks.


Many experienced divers struggle with a sobering reality: Overfishing and a long list of other human factors have systematically reduced the oceans to a shadow of their former glory. “You should have seen it before” is a phrase we hear all too often, and in most cases the depletion is indisputable. It can weigh heavily on the souls of passionate divers, but the whale-shark aggregation off Isla Mujeres offers us a reflection of a time long past — a time before we exhausted the inexhaustible, a time of abundance, of massive migrations and unimaginable aggregations. It speaks of wonders yet undiscovered and of the resilience of the oceans if they are given a chance. If a gathering of hundreds of whale sharks can go unnoticed so close to a major city, what else is still out there yet to be discovered? For me, this aggregation is message from the oceans that there are wonders still worth protecting. But we must act now before they, too, become shadows in the past.

The Great White Sharks of Guadalupe

By Stephen Frink

In the world of shark diving, complaints by irritated anglers who cannot land whole fish make for encouraging and tantalizing leads. It was just this sort of frustration that first led divers to Mexico’s Guadalupe Island in the late 1990s. Aggravated fisherman following the tuna migration 150 miles west of Baja California seemed to be bringing tuna heads onboard as often as tuna, and so a few daring souls eventually decided to venture in and see what was down there. Those first snorkelers didn’t stray very far from the swim platform while viewing the 14-foot great white sharks, for no one knew much about how the sharks would react. But when stories of seasonally consistent encounters with these huge fish and water clarity of 100 to 150 feet began to filter back, dive boats equipped with shark cages and surface-supplied hookah rigs became the next wave of Guadalupe tourism.

For several years there were only a couple of rustic, albeit seaworthy, fishing boats making the 20-hour steam from marinas in San Diego or Ensenada to the 22-mile-long volcanic island. But lately, shark viewing in Guadalupe has ramped up in popularity, and the fleet has improved dramatically. There are usually five or six vessels anchored in the protected bay during the heart of the season, which runs from early August through November each year. Many of these are upscale liveaboards with multiple surface and subsurface cages tethered to their sterns. Charters are typically six-day, five-night affairs. Given the time invested running to the island and the capricious nature of intimate shark encounters, spending any less time would be counterproductive.

Half the body of a great white shark follows some fish

Regulations, too, have changed. In the old days, 45-gallon drums of blood and chum were constantly ladled into the sea to create a chum slick. This attracted sharks to the boat, and tuna throw-baits were used to lure them to the cages and, ideally, directly to the cameras’ domes. But these sharks are now well conditioned to the presence of boats and cages, which makes encounters exceedingly reliable. The large quantity of bait is no longer necessary to attract them to viewing distance. This is just as well since the Mexican government has declared the region a Biosphere Reserve, protecting not only great white sharks but other important marine species including the Northern elephant seal and the Guadalupe fur seal. The government contends that excessive baiting of the sharks will change their natural behavior and may even cause injury to them if they run into a cage while aggressively pursuing throw-baits. So smaller amounts of chum are now deployed but in different ways. The end result is that shark encounters are dependable, and viewing conditions are the best anywhere on the planet for Carcharodon carcharias. What’s more, there are lots of sharks. Dive boats have reported as many as 109 individuals in the bay at the northeast end of the island.

The In-Water Experience

While the water clarity at Guadalupe is often exceptional, the near-shore water can be quite turbid. Depending on whether the currents are carrying elephant-seal detritus toward the boats, visibility and particulate matter may affect photographs. But overall, compared to the other global hotspots for white-sharking (South Australia and South Africa), Guadalupe is the king of clarity.

After the long trip out to the island you’ll want to spend as much time as possible in the water once you’re there, so be prepared to suit up for 69°F water. Most cage shifts are 60 minutes long, so gauge your need for thermal protection accordingly. I have been comfortable in a 7mm wetsuit and hood, but you will likely see drysuits on many of your cage mates.

Most shark cages are designed to float on the surface tethered to the stern of the boat. Breathing is done using a surface-supplied regulator, and the boats will often provide weight harnesses so the heavy load of lead required to offset suit buoyancy near the surface is carried on the shoulders as well as the hips. There will be long rectangular slits in the cage large enough to accommodate a big dome but small enough to keep the business end of a great white shark outside. Some boats also provide subsurface cages. These can be suspended at 30 to 40 feet, allowing a different perspective of the sharks’ approaches and even an upward view toward the other cages.

Photo Tips for Guadalupe

Diver's two arms come out of shark cage in an attempt to photograph a shark

In our ship’s briefing the captain asked for any photographers on board to raise their hands. I expected there might be six or eight of us, but incredibly 24 hands shot up. There were no nonphotographers on the trip. Of course, the definition of “photography” varied; some divers used expensive, housed digital single-lens reflex cameras with strobes, while others were perfectly content to use point-and-shoot cameras with small, plastic housings. One girl confirmed her photo passion was using a wet-case to protect her iPhone. These sharks are such compelling subjects and the adventure so memorable, one is compelled to take stills or video by whatever means available. To that end, here are a few tips:

  1. The cages are fine for four people, unless one of the four has giant strobe arms. You don’t necessarily need dual strobes, but if you use them make sure the arms articulate easily around obstructions in the cage. A single, quick-recycling strobe is ideal.
  2. I often used a 16-35mm zoom, but many of my best shots were at 35mm end, which meant the sharks weren’t always all that close. Sometimes they did come within 2 feet, and those were my best shots from the trip. Even in crystalline visibility, resolution and color will suffer in photos taken from 8 to 10 feet away.
  3. A fast shutter speed is a good idea. At least 1/250 second is advisable because both the shark and the cage will be moving. Multiple shooters will be jockeying for the best angle, and their in-cage movements may make it tough to hold steady. All of this is exacerbated if there is surface chop as well. Fortunately, modern cameras perform well with high ISO settings, so operate at the highest strobe synch speed, and you should be OK.
  4. Consider handholding your strobe. I like to be nimble in aiming my strobe light, moving it backward to minimize the light on the sharks’ white bellies or moving it to the side if a school of shiny fish is situated between me and the shark.
  5. Some may choose to shoot with available light, and in the very shallow water of a surface cage that will work fine. But this leaves the underside of the shark in shade and won’t dramatically illuminate the teeth. It will work, but better shots will come from artful application of strobe light.
  6. Don’t forget about the video capability of your camera. Search “great white shark” on YouTube and you’ll get about 25,000 results, a confirmation of the validity of this subject for moving pictures. These sharks are far more accessible today than they were a decade ago, and the evolution of Guadalupe as the premier white-shark destination has much to do with this.

© Alert Diver — Q3 Summer 2012