Note: Peter Benchley died February 12, 2006. He was my friend and I feel immensely honored to know that.

I met Peter in 1980 as together we embarked on an expedition to make a film in the Sea of Cortez. The film crew was a magical group. Michele was with us and we were yet to be married at the time. Marty Snyderman was along as was one of Peter’s best friends, Stan Waterman. To say that it was a wonderful trip seems inadequate. But indeed, it was a trip of wonders. One of the wonderful things that happened during the two weeks we spent making the film glided up to us in the form of the largest manta ray I have ever seen. Its wingspan approached 18 feet. When I first saw the giant ray Stan, Peter and I were returning from a dive to film the giant schools of hammerheads that often darkened the liquid skies above the Marisula Seamount (El Bajo). Michele was riding on the back of the enormous ray trying to remove a tangle of fishing net that was wrapped around and embedded in the flesh surrounding one of its cephalic fins. As the ray carried her off into the dark water beyond the Seamount, Stan and Peter were mesmerized by the fantastical image of the young girl aboard the great winged beast. The sight inspired Peter’s next book, The Girl of the Sea of Cortez. I, on the other hand, was terrified that I might not ever see Michele again.

Fifteen minutes later, the ray returned to the Seamount. The fishing net was gone and Michele was still riding on its back. Low on air, she dismounted and headed back to the boat. The ray followed her back to the swim step.

In the days that followed, the great ray offered rides to each member of our crew. Certainly the animal, now recovering from its wounds, believed divers to be highly beneficial cleaner fish. Just as certainly, without Michele’s help, the ray would have died.

Today riding on the back of mantas and whale sharks is considered ethically inappropriate. And rightly so. But thirty years ago there were far fewer divers, far more many mantas, and those of us privileged enough to see one, were blissfully naïve.

I wrote the following story after returning from the expedition. Reviewing it now, I can’t believe how much things have changed in just a few short decades. Today it is rare to see a single hammerhead or a manta ray at the Marisula Seamount. Gone are the vast schools of fish. Gone are the legions of hammerheads. Gone are the giant groupers. And I have no doubt that in the following months the great ray that Michele rescued found its way into another net. The Marisula Seamount is no longer a world class dive. It’s just a lonely rock covered by an increasingly empty sea.

Undersea Fantasy in The Sea of Cortez

Howard Hall

©Howard Hall

Millions of years ago, in our planet's relatively recent geologic past, the pacific coast of northern Mexico was ripped away from the mainland by violent earthquakes. The resulting fissure was nearly 800 miles long and many thousands of feet deep. In the south, it ripped through the coast and into the Pacific Ocean. A spectacular torrent of ocean water rushed into the void as if an incomprehensibly enormous damn had collapsed.

Some authorities believe that the Sea of Cortez, also known as the Gulf of California, was created in one cataclysmic event. Others feel that a series of earthquakes along the San Andreas Fault created the Sea over a relatively short expanse of geologic time. In either case, that ancient sea was much different than the Sea of Cortez today. The hot waters have cooled and the earthquakes have diminished. But the sea remains far from calm.

The deep ocean floor of the Sea of Cortez is still tearing apart, and the gap between mainland Mexico and the Baja peninsula continues to widen a few inches every year. At the deepest points of the Sea, the tearing of the Earth's thin crust exposes red hot magma to the cold deep waters. These waters are heated and rush toward the surface and, along with the enormously strong tidal forces, they contribute to the massive upwelling of nutrient rich deep sea waters. In many places, especially in the midriff area of the Sea of Cortez, these deep, cold waters can be seen boiling up on the surface. During the winter the upwelling helps push the surface temperatures down to 60 degrees F. In the summer, however, the relentless summer sun pushes the water temperature up to nearly 90 degrees F.

This combination of massive upwelling of cold water nutrients and tremendous temperature fluctuation has created one of the most unusual and exciting marine environments on the planet. The Sea of Cortez literally boils with life! The upwelling nutrients give birth to dense blooms of plankton which in turn form the base for the Sea's food chain.

The strong tidal currents sweep the plankton by the numerous islands and along the coast. In areas exposed to the rushing currents, marine invertebrate life is lush and exquisite. Many of these invertebrates reach out into the current through various mechanisms to filter out the passing plankton. The filter feeders are then prey for carnivorous invertebrate forms. Tiny fish also feed upon the drifting plankton and they are then fed upon by larger predators.

The marine wilderness in these current-swept places is a diver's paradise. Colors explode from the faces of undersea cliffs like fireworks on a Fourth of July night. Among the brilliantly colored sea fans, sponges, and corals, the numbers of invertebrate species are too numerous to count. And in this remote wilderness, many are little known to science and some remain undescribed.

Animas Island, 50 miles north of La Paz, lies in the prevailing current. It is a tiny rock of an island with steep ocean cliffs and little protection for the occasional boat that passes there. Below the ocean surface, the steep sea cliffs continue down into the deepest depths of the Sea. The northern side of the island faces into the current which rushes by the undersea cliff face like ocean winds sweeping coastal bluffs. The marine wilderness there is one of the most beautiful in the Sea of Cortez.

As the diver descends into the abyss along the cliff face, the invertebrate life grows richer. Many of the small benthic fish and invertebrates are ingeniously camouflaged to match their habitats. Yet, this cryptic coloration is not the drab grays and browns of terrestrial camouflage. In a world so filled with dazzling color, these animals are marked in almost unbelievable brilliance and these colors effectively blend into the colorful background. Sometimes, perhaps influenced by the narcotic effect of high pressure air, a diver might feel as if he were in an artificial world created by Walt Disney. It sometimes becomes difficult to believe that a world of such beauty exists in an environment that is alien to man and seen by almost no one.

Just as areas exposed to the flow of the currents proliferate with benthic life, areas protected from the currents are devoid of it. This is one of the most intriguing features of the Sea of Cortez. The marine environments vary greatly with their position in the current. One island may be an undersea fantasy land, while another just a few miles away, is all but barren. The undersea wilderness of the Sea of Cortez varies greatly from on place to another since the temperature of water and exposure to current is highly variable over short distances.

©Howard Hall

A few miles southeast of Animas is Isle San Jose. It is a large island and because of its size, much of the coastline is protected from the currents. The protected coves and rocky shores are almost devoid of marine invertebrate growth. And though there are great numbers of fish along nearly any shore of the Sea of Cortez, the size and number of fish is much less in these protected areas.

The strong currents rush around and past San Jose Island. South, the current passes through a large expanse of open sea before reaching Espiritu Santo Island 20 miles away. There is just one feature in this path to interrupt the flow. It's called the Marisula Seamount, also known as El Bajo.

Ages ago, volcanic activity thousands of feet under the sea pushed the seamount up to within just sixty feet of the surface. It almost became an Island - almost. Instead this great mountain exists totally submerged and, until recently, unseen. Hundreds of years ago, and perhaps thousands, fishermen discovered the seamount and found it to be a highly productive fishing ground. Then, only a few years ago, a diver noticed that the fishermen were anchoring on an object in the open sea and for the first time a human descended to the top of the spire to witness the most spectacular marine environment in the world.

It is not for the beautiful colors of the invertebrates and small benthic fish that divers from the world over now travel the Marisula Seamount. It is for the almost unbelievable adventure and the realization of childhood fantasy that they come.

Here the plankton-rich current rushes over the top of the spire and concentrates an entire marine eco-system into an area only fifty yards in diameter. The top of the seamount is a tiny plateau of land where the current born plankton feeds myriad species of small fish which are then fed upon by larger and larger fish in turn. But it is the great predators at the top of the food chain that the Seamount is famous for, and here these mammoths exist in numbers seen nowhere else on Earth.

You can't blame a diver for feeling somewhat tentative as he descends the anchor line for his first visit to the Marisula Seamount. The stories he has undoubtedly heard sound much too fantastic to have any base in reality. Yet the stories are true. On his way down to the summit he might see anything. There are great bill fish passing through the enormous schools of tuna and jacks on the surface. When a half-ton marlin rushes through the fleeing schools there is a sound like distant thunder as thousands of fish dash away from the slashing bill. Sailfish often pass within a few yards of the anchor line as the diver descends.

Finally, the bottom comes into view. It is a large rock that seems to hang suspended over the fathomless depths. On all sides of the Seamount the water is dark blue - black. There is a large black rock that seems to stand out conspicuously. But when the rock moves that diver realizes that it is a gigantic grouper. The fish may weigh over 500 pounds.

When the diver reaches the bottom he might kneel on the top of the spire and wait. There is nowhere to go since the surface of the Seamount is small and the walls plunge off vertically to depths beyond the diver's safe range. So he will just stop and wait and watch.

In the deep water north of the Seamount hammerhead sharks accumulate in astounding number. They form great schools of four or five hundred sharks, each animal in the eight to ten foot range. Occasionally, the Seamount lies in the school's wandering path. At first the horizon above the Seamount seems to grow suddenly dark. Then as the diver strains his eyes into the darkening water at the edge of visibility, individual sharks take form. As the school approaches, hundreds of sharks become visible and soon the school fills the water above the Seamount. Panic would surely set in with most divers if they hadn't been told repeatedly that these schools never show any interest in divers.

Certainly the Seamount's strongest attraction for divers is the manta rays. Seeing one of the majestic creatures, with wing spans approaching twenty feet, is an experience to be remembered. But at the Seamount the mantas are more of a phenomenon than just a large marine creature. They are a phenomenon because for some unknown reason, these animals actually encourage contact with humans! As a diver waits at the edge of the Seamount, a huge winged manta will often rise up from the depths beyond the spire and pause a few feet away. If the diver is gentle he can swim to the ray and stroke its stomach or back. As he does this, the manta's horns begin quivering and the trailing edge of its wings begin to flutter. Then if the diver wishes, he may climb onto the mantas back, grasp the great shoulders and go for the ride of his life!

This is truly fantasy come true. Words are entirely inadequate in describing the sensation of flying off into the dark water beyond the Seamount's edge aboard a great winged beast. The enormous wings beat and the water rushes by your face like a strong wind. And you see wonderful sights traveling silently many times faster than a diver can swim. Fantasy writers have been trying to describe the sensation of riding on the back of a great bird for centuries, but their stories come up short of the actual experience. On the back of a great ray, reality becomes fantasy and fantasy becomes real.

As spectacular as the manta phenomenon is at the Marisula Seamount, there is one other experience that is more thrilling. There is a creature that is greater and more awesome. It is the largest of all fishes and the largest of all sharks. It is the whale shark.

Occasionally a whale shark passes by the seamount. It may be nearly fifty feet long and weigh more than twenty tons. Like the manta rays, the whale shark is a plankton feeder and would never intentionally harm a diver. And, like the mantas, the whale shark permits riders.

Peter Benchley ©Howard Hall

Whale sharks don't encourage riders like the manta rays do. But they don't discourage them either. Divers are simply so small compared to the massive size of the whale shark that they fail to arouse the animal's attention. The great fish seems to take little notice and the diver soon begins to feel like a flea on the back of a great beast. As the diver holds fast to a pectoral fin that is larger than his entire body, he feels a joy and exhilaration like no other. There is a sensation that the shark is holding still and that the ocean is rushing by.

In 1979 Peter Benchley, author of Jaws and The Deep, was a member of one of the first expeditions to the Marisula Seamount. He was one of the first to discover these strange and wonderful phenomenon, and was one of the first to ride the mantas. The experience inspired his next novel - THE GIRL OF THE SEA OF CORTEZ.

Just as this wonderful sea had a profound influence on Benchley, it similarly influences all who dive there. This marine wilderness is a place where the rules of life are seemingly suspended. Kneeling on the edge of the Marisula Seamount in an alien environment seen by very few humans on Earth, the distinction between fantasy and reality becomes unclear and childhood dreams come true.