Sixty Fathoms Under the Sea

A wildlife filmmaker braves the bends and other hazards to explore and chronicle a largely unknown, threatened deepwater ecosystem

  • Howard Hall
  • Apr 01, 2003

FROM THE DECK of our boat, the mount we saw under the water appeared to be just another beautiful Fijian coral reef. Situated between the islands of Viti Levu and Vanua Levu, it was roughly circular and about 200 yards in diameter, a mosaic of iridescent gold and turquoise surrounded by a placid sea of indigo blue. It was named Mount Mutiny for its association with the infamous Bounty (Captain William Bligh passed by here in 1787 after being set adrift in a launch by mutineers), but otherwise seemed nothing special.

The digital depth sounder in the bridge of our boat, Undersea Hunter, told a different story, however. As we circumnavigated the reef, the display on the depth sounder was blank. Although able to sense the ocean floor more than 1,000 feet underwater, the sounder could find no bottom. It seemed impossible, but this tiny reef was shaped like a needle thrust up from the ocean floor. If placed on land, this narrow spire would overshadow the world's highest skyscrapers.

Just as Undersea Hunter nearly completed her trip around the mount, the depth sounder momentarily recorded a ledge at 350 feet. Our captain threw the ship into reverse. We had found our dive site.

I had come to this remote tropical location with a crew of 20—including divers, filmmakers and scientists—to capture the hidden world of a deepwater coral reef on large-format motion-picture film. With this dive and several others below 300 feet, I hoped to chronicle the largely unexplored deep reefs—and perhaps the discovery of new aquatic species—with two giant underwater cameras. In addition to showcasing the beauty of these habitats, the IMAX® production we were filming—titled Coral Reef Adventure—would also sound an alarm about the threat to reefs from global warming, siltation and overfishing. These dives would test the limits of our equipment, skill and endurance, however. Experts warned that we stood a 30 percent chance of suffering a life-threatening case of the "bends" (decompression sickness) on our descents below 350 feet.

A few hours after mooring the Undersea Hunter to the side of Mount Mutiny, I was rocking gently in the dive skiff watching the numbers on my digital dive watch tick by. We had given an advance team of three support divers a five-minute head start. They were descending to 100 feet with the two cameras and an assortment of scuba tanks—equipment we would pick up on our way to the deep ledge.


RAPTURE OF THE DEEP: For a film on coral reefs, the author and his team made dozens of dives in the Fijian archipelago, where brilliantly hued sea fans, tree corals and fish abound. A primary goal of the film was to bring to light the little-explored realm of the deep reefs.

My watch ticked over to display five minutes. "Okay, guys," I said, "time to go." Instead of standard scuba tanks, we wore special devices called closed-circuit, mixed-gas rebreathers—machines very similar to astronauts' life-support systems. We went through our safety checklists and one-by-one began slipping over the side of the skiff.

As we drifted down toward the edge of the reef, we passed myriad colorful fish, several enormous sea anemones surrounded by their anemonefish tenants, a pair of hawksbill turtles and an artist's pallet of colorful hard and soft corals. It was spectacularly beautiful, but as I took in these wonders, the experience was tempered with a twinge of sadness. When my wife, Michele, and I had scouted Fiji's reefs in April 2000, they were much different.

Back then, the weather pattern known as La Niña (which often follows the more infamous El Niño) brought warmer water to the area around Fiji. As water temperatures soared past 86 degrees F, amber-colored algae, which live symbiotically within transparent coral tissues and supply coral animals with nourishment, began to leave their hosts. Without the algae to supply the coral animals with food, corals starve and eventually die. The process is called bleaching and, ironically, in its early stages it can be beautiful. Michele and I were dazzled as we swam above the reefs that spring. Normally brown corals, now white as bone, branched out in stark contrast to surrounding bouquets of pink, purple and yellow soft corals. But when we returned to Fiji the following November to begin filming, the bleached coral had died, leaving dusty gray skeletons.

The bleaching episode in Fiji is not an isolated incident. The Great Barrier Reef in Australia has recently experienced the worst bleaching epidemic in its known history. Today, a total of 25 percent of the planet's coral reefs have been destroyed. Of the reefs that remain, half or more may die during the next 30 years, many scientists say. Global warming contributes to the increasing water temperatures that seem to cause coral bleaching. But bleaching alone cannot account for the dramatic loss of reefs worldwide. Many other factors are at work: Coastal development and deforestation choke rivers with silt that spills into the oceans and smothers reefs. More than one-third of the coral reefs surrounding thousands of Philippine islands have been destroyed by siltation due to logging, for example. Also, overfishing decimates populations of fish that keep reefs healthy by grazing on algae that would otherwise smother coral. In addition, pollution poisons reef-building corals or promotes algal blooms that overwhelm them. There is even evidence that deforestation in Africa has caused dust storms that sweep algal and bacterial spores high into the atmosphere to settle on coral reefs thousands of miles away, causing epidemics of coral disease.

Although thoughts about threats facing reefs momentarily distracted me during our dive at Mount Mutiny, I had to return to the task at hand. We were now 100 feet below the surface, where we joined our support divers on a six-foot-wide terrace jutting out from the reef wall. Our first task was to adjust the breathing gases in our rebreathers to cope with the extreme depths. The air we breathe at the surface would kill a diver below 300 feet, because the nitrogen content becomes increasingly narcotic, causing "rapture of the deep," and the normal oxygen content becomes poisonous. So I reached down next to my left hip and turned off the valve supplying air to the breathing circuit. Then, I switched on another valve that would inject helium into the breathing mixture for the rest of the descent, replacing nitrogen and eliminating the threat of nitrogen narcosis. The computer in my rebreather would automatically maintain the oxygen levels at less than 10 percent as I descended.

After switching gas supplies, cameraman Bob Cranston and I took the movie cameras from our support divers. Above the surface, my camera weighed more than 300 pounds and Cranston's weighed about 150 pounds. Underwater, they were designed to be neutrally buoyant, weighing nothing. But moving such massive systems against even the mildest current could be a struggle. Both were fitted with air tanks and regulators that allowed compressed air to be pumped into the housings. Without this feature, the cameras would crush like paper cups in the extreme pressures below 200 feet.


REEL JAWS: While filming in the South Pacific, the author (holding the movie camera, left) came upon a swarm of gray reef sharks taking shelter from powerful ocean currents in a canyon.

I stood on the terrace and looked down into the clear, blue-black water. I could see nothing except a shear wall extending into the abyss below. We were about to begin a freefall that would take us another 250 feet straight down to a place not before seen by humans. I hoped the Undersea Hunter's depth sounder had not recorded a school of fish at 350 feet instead of a narrow ledge. I pushed the button on my underwater microphone and said, "Okay, guys. Let's go." Then I stepped off the edge and began to fall.

The descent was like skydiving in slow motion. Eventually, I saw a blue shadow below. We had found the ledge. We landed and I knelt on the bottom and took irregular deep breaths. My hands were shaking from what some divers refer to as "helium jitters," a temporary syndrome often experienced at great depths. I knew this would pass after a few minutes, so I used the time to look around and allow my eyes to adjust to the dim twilight of the deep reef. I checked my instruments, and my depth gauge read 365 feet.

I had landed next to an enormous sea fan, more than six feet high, that looked pink under my small dive light. At the base of the sea fan was a large branching growth of ivory-white lace coral. The lace coral's color was not the result of bleaching. At this depth there is not enough light for algae to convert sunlight into energy for corals. Instead, lace corals survive by capturing plankton with hairlike stinging tentacles that extend into the current. Neither the sea fan nor the lace coral was of a kind I had seen before. Indeed, as I looked around, all of the corals appeared unfamiliar.

The fish were strange, too. In the dimness I had trouble seeing their shapes distinctly. When I shined my light on a fish, I'd spy a quick dance of color before it streaked for shelter. Could it be an undiscovered species? When my breathing returned to normal and I rechecked all my instruments, I powered up the camera and began moving down the slope toward Richard Pyle, an ichthyologist at the Bishop Museum in Hawaii who accompanied me on the dive.

Pyle already had his hand nets out and was in hot pursuit of a fish. He followed his prey to the reef's edge, and for a moment seemed to consider swimming over the edge to follow. Then he turned, glanced at me and set off after another fish he spotted next to a huge boulder. Cranston moved his camera to the top of the boulder to get a shot looking down on our group as Pyle pursued fish. Our two assistant divers, Mark Thurlow and Dave Forsythe, hovered nearby and illuminated Pyle with their lights—ready to take a camera or pass a scuba tank if something went wrong.

Pyle had found an ichthyologist's El Dorado. Within minutes he had captured a half dozen fish, some new to science. Each time a fish went into the collection bottle, Pyle would look up, point at another fish swimming nearby and yell through his rebreather mouthpiece. I couldn't understand what he was saying, but it was obvious he was excited.

I positioned myself next to the boulder, focused the camera and prepared to punch the "run" switch. This was the moment of truth: Because of the limitations of large-format equipment, I could expose at most only three minutes of film before the film ran out. Cranston could expose another 90 seconds with his camera. At worst, both cameras would jam, leaving us with three hours of decompression before surfacing and a wasted day. On more than half of the deep dives we made for Coral Reef Adventure, one or both of our cameras failed under the difficult conditions.

I hit the switch and was delighted to hear the camera whirring. Pyle had already selected his next target—a brilliant eight-inch-long purple and yellow fish hovering above a small sea fan—but waited until he heard the camera running before moving in with his net. He swooped and missed. But the fish dashed up and Pyle's second sweep was successful. He held up the captured fish to show me and the camera, yelling through his mouthpiece, "It's new, it's new!" Then, as if choreographed by a Hollywood director, three enormous hammerhead sharks passed overhead, their pale underbellies illuminated by our lights. I looked up at Cranston and he gave me a thumbs-up. His camera had run flawlessly as well.

After just 30 minutes on the bottom, it was time to make the long ascent back to the boat. We had to stop at regular intervals to allow nitrogen and helium to gradually leave our body tissues, thus preventing the "bends"—a process that took more than three hours. Pyle used this time to relieve pressure from the swim bladders of his captives with a tiny hypodermic needle. These prizes were destined for scientific study at the Bishop Museum.

The long ascent gave us an opportunity to review the brief, rare view we had gotten of "the twilight zone." Below 250 feet, virtually all coral reefs are unexplored, and Pyle believes there may be as many as 2,000 new species in this zone in the tropical Pacific alone. As the world's coral reefs decline, he is in a desperate race to identify as many of these species as possible. During our deep dives in Fiji, Pyle discovered five new species. Each will require months of study before being awarded a scientific name. Meanwhile other species are vanishing from these reefs before they're even discovered. "It's an even greater tragedy when an undiscovered species becomes extinct," says Pyle. "Not only did we never know it even existed in the first place, but we never learn the critical way it contributed to the reef's ecosystem."

Recognizing that most of the world's remaining coral reefs could be gone within our lifetime, Michele and I feel a similar urgency to capture the splendor of this ecosystem on film. Our hope is that productions such as Coral Reef Adventure will contribute not only to the public's understanding and appreciation of reefs, but also to the protection of these crucial ecosystems.

Californians Howard and Michele Hall have produced many natural history films for television and several IMAX® films for theaters. Howard Hall is director of underwater photography for Coral Reef Adventure.

Bringing Reefs to The Giant Screen

Coral Reef Adventure takes viewers to some of the South Pacific’s most beautiful underwater environments. Following the expedition of cinematographers Howard and Michele Hall, the new giant-screen film examines the behavior of marine animals and the current state of fragile coral-reef ecosystems. The film was produced by MacGillivray Freeman Films in association with NWF and directed by Greg MacGillivray. For more information, including a listing of theaters where the film is screening, see

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