A Coral Reef Adventure

by Howard Hall

Divers preparing to descend.© Michele Hall

Mark Thurlow, Dave Forsythe, and Richard Pyle slipped over the side of the Undersea Hunter’s skiff and waited while Michele Hall and Betty Almogy passed each an 80 cubic foot tank filled with trimix bailout gas. Bob Cranston and I followed and because we would both be wielding massive Imax cameras during our 350-foot dive, we each received less cumbersome 40 cubic foot bailout tanks. After side-mounting the 40 by clipping it to the D-rings on my Scubapro Stab Jacket, I switched on my highly modified Biomarine 15.5 rebreather, set the PP02 level at 1.30 ata., and descended 100 feet to a small ledge that jutted out from the shear Mt. Mutiny escarpment. Only two hundred yards in diameter, the Mt Mutiny reef rises to the surface from over a thousand feet of oceanic water between the two main Fijian islands, Viti Levu and Vanua Levu. And like nearly all coral reefs, we were sure that, below 250 feet, Mt. Mutiny was entirely unexplored.

Looking down from the 100 foot ledge, the water was nothing like the iridescent blue that one comes to associate with coral reefs of the tropical Pacific. Instead, it was dark cobalt blue, almost black. I reached back and turned off the valve to my rebreather’s air diluent tank. Then I purged the low-pressure lines in my rebreather by pressing the inflation button on my stab jacket to confirm that the air diluent was off . After purging the lines and dumping the BC, I turned on the valve of a second diluent tank filled with a mixture of 90% helium and 10% oxygen. With a nitrogen narcosis level locked in at an equivalent air depth of about 100 feet, my rebreather would now begin adding helium to make trimix as I continued my descent. Finally, I keyed the microphone on my OTS communications system and verified that Bob, Dave, Richard, and Mark had also switched their gases. After a brief check of each other’s equipment and a quick glance at the check lists we had strapped to our left wrists, the five of us pushed off the edge of the cliff and began falling into the abyss.

At 150 feet, we met Peter Kragh and Rob Barrel who were waiting with two cumbersome IMAX camera systems on the descent line we had dropped over the Mt. Mutiny wall. Peter passed me the Mark II camera, an enormous monster that weighed nearly 300 pounds above the surface. This beast was challenging enough to push around in shallow water despite being neutrally buoyant. On deep dives, the overexertion caused by wielding the bulky camera was our primary concern. Bob received the IW-14 camera, a smaller 150 pound system that, though less massive, was still more than a handful. Having Peter and Rob meet us at 150 feet with the cameras saved us some energy. They would also relieve us of the cameras during our long ascent. Wearing an Inspiration, Peter would wait for us at the 180 level where he had tied off an additional air bailout tank while Rob would move into shallow water to wait. In addition to the air bailout at 180 feet and the trimix bailout tanks each member of the deep team side-mounted, we had 50/50 nitrox bailout staged at seventy feet and pure oxygen bailout staged at 25 feet. Once we reached shallow decompression, Cat Holloway would join Peter and Rob to help shuttle gear to the surface.

After accepting the Imax cameras from Peter and Rob, we began the final 200 foot descent. Like skydivers falling in slow motion, we plummeted straight down the shear wall. The water below became blacker as light levels dropped. As we descended past 200 feet, all hint of color vanished. Soft corals that were red, pink, blue and yellow all looked much the same. As it grew darker, it became difficult to see into the shadows beneath draping soft corals and at the openings of small caves. We had entered the “twilight zone.”

At 260 feet we came to a shelf that extended twenty feet out from the wall and where enormous gorgonian corals formed a small forest. Where the shelf intersected the reef, a dark shadow loomed fifteen feet high - the opening to a large cave. As we dropped past, I strained to see how far back it goes, but it was too dark. We plummeted past the ledge and continued to fall. I watched my depth gauge and other instruments carefully as we fell past 300 feet, then 320 feet.

As we passed 330 feet, I began injecting gas into my stabilizing jacket to arrest my descent and gently settled on a ledge about forty feet wide. My depth gauge read 344 feet. My breathing was jerky and uneven, and my hands seemed shaky. I had helium jitters. I knew if I held still for a few moments, the sensation would pass. I used the time to look around and try to get a sense of this alien place. The wall next to me was covered with small and delicate soft corals. A light dusting of pure white sand frosted every tiny ledge and soft coral branch. The sand was so white it seemed to glow faintly in the dim light. I realized that the sand here was extraordinarily white because no green or brown algae can grow in it at this depth. The scene reminded me of a fresh mountain snowfall viewed in the darkling light of a full moon. Despite feeling a bit strange, I rejoiced in the certain knowledge that no one had ever been here before.

After a few moments, my breathing returned to normal and I began rechecking my instruments: depth, decompression computer, oxygen pressure, heliox pressure, rebreather primary display, and oxygen sensor display (usually called a secondary display). Everything seemed in order. Next I began powering up the camera. While I was busy with the camera, Bob moved over to me and said something to me through his underwater microphone. He sounded like Donald Duck with a mouthful of marbles. I couldn’t understand a word. I keyed my microphone and said, “What?”

“Did you check your 02,” Bob mumbled. I made out about half the words this time, but it was enough to understand his meaning.

“Okay, okay,” I responded. Our OTS communication system is a prototype. Push to talk microphones had been mounted inside our rebreather mouthpieces. Although this system eliminated the often-problematic use of a full-face mask with rebreathers, it required that the diver talk around the mouthpiece. Although this makes talking difficult and transmissions imperfect, we’ve found that with practice the mouthpiece microphones are very adequate. Today all members of our film crew are equipped with this system whether on closed circuit or open circuit.

Bob was concerned about my 02 level because on a previous Coral Reef Adventure expedition I had neglected to make a PP02 switch when I reached the bottom on a 365 foot dive (switching PP02 levels in order to avoid spiking oxygen pressure during descent is a step we later determined unnecessary). This error combined with overexertion from pushing the Imax camera around and a bit of bad luck resulted in a serious neurological bends hit during my 50-foot decompression stop. The symptoms disappeared after descending to 100 feet where I resumed extended decompression. I left the water symptom-free but when some numbness appeared later in the day, I went back in the water and spent four hours following the Australian in-water recompression protocol. The next day I began four days of chamber treatments in Suva. Although I survived without residual damage, the incident had been sobering. But every member of our crew knew that these dives were pushing the envelope. And pushing the envelope had been one of our intentions.

When Greg MacGillivray, director of the giant format films Everest and The Living Sea, asked Michele and me to work with him to make a film about coral reefs, we were immediately enthusiastic. When Greg said he planned to call the film Coral Reef Adventure, I began thinking about what we might do that would justify the title. MacGillivray Freeman films are always made to the highest standards. So if it was going to be called an adventure then I wanted the adventure to be real. True adventure is real when the passion to explore the unknown is only slightly stronger than the fear of it. I asked myself where, after thirty-five years of diving, remained for me to explore. I immediately realized the answer was everywhere below 250 feet. Then I asked myself if the prospect of attempting to take an Imax camera down below 350 feet frightened me. The answer was yes, the idea was terrifying. I discussed the idea with Bob Cranston and Mark Thurlow. They were both thrilled by the idea. Thrilled and terrified. None of us had ever been below 250 feet.

After powering up the Imax camera, I followed Richard Pyle down the slope to where the reef falls off once again into the abyss. Richard has become legendary among tech divers and ichthyologists. During recent years he has combined both disciplines to discover dozens of new fish species on that part of the deep reef he calls “the twilight zone.” Recording Richard’s capture of a new species of fish was our primary objective during our series of deep dives.

Richard already had his hand nets out and was in hot pursuit of a fish. He descended, following his prey to the reef’s edge at the bottom of the slope where it tried to elude him by darting over the edge. Richard followed, disappearing behind the reef wall. My depth gauge read 370 feet. Richard was now below 400 feet. No way was I going to follow Richard over that shear wall with this 300-pound camera. Just as I turned to move up the reef, Richard reappeared and began moving up the slope to where a large boulder came to rest after separating itself from the reef wall eons ago. There Richard immediately sighted another interesting specimen.

Bob Cranston moved to the top of the boulder to get a shot looking down on our group as Richard pursued fish. Mark and Dave hovered nearby illuminating Richard with their lights and standing by to take a camera or pass a bailout tank if something went wrong. Richard Pyle was in fish nerd heaven. Next to the large boulder he had found an ichthyologist’s El Dorado. Within minutes he had captured a half dozen fish, some almost certainly new species. Each time a fish went into the collection bottle, Richard would look up, point at another fish swimming nearby, and yell through his rebreather mouthpiece (Richard’s Cis-Lunar rebreather was equipped with receive but not transmit communications). It was impossible to understand what Richard was saying, but it was obvious he was seeing one exciting new species after another. I positioned myself next to the boulder, focused the Imax camera, and prepared to punch the “run” switch. This was the moment of truth. At best, I could expose three minutes of film before the camera magazine was empty. Bob could expose another 90 seconds with his smaller camera. At worst, both Bob’s and my camera would jam leaving us with three hours of decompression before surfacing and another day of film production lost with nothing to show for it. In the end, more than half of the twenty-one deep dives we made for Coral Reef Adventure, one or both cameras failed. These failures were usually the result of the cameras’ inability to operate reliably in gas densities greater than ten atmospheres. In order to take camera housings below 300 feet which would normally crush like tin cans at 200 feet, we had modified the housings with gas supplies and pressure regulators allowing the housings to be pressurized during descent.

I punched the “run” switch and was delighted to hear the camera ramp-up to running speed. Richard had already selected his next target but waited until he heard the camera running before moving in with his net. A brilliant eight-inch long purple and yellow fish hovered above a small sea fan. It was like nothing I had seen before. In fact, it was like nothing anyone had ever seen before. Richard swooped in with his net and missed. But the fish dashed up away from the reef instead of down. Richard’s second sweep with the net was successful. He was enormously excited as he held the captured fish up to show me and the camera. Through his mouthpiece he was yelling, “It’s new, it’s new!” Then, as if choreographed by Greg MacGillivray himself, three enormous hammerhead sharks passed overhead, their pale underbellies easily illuminated by the glow of Dave’s and Mark’s hand lights. I looked up at Bob and he gave me a thumb’s-up. Surprisingly, his camera had run flawlessly as well.

After thirty minutes on the bottom, it took our team over three hours to ascend. Richard used the decompression time to relieve pressure from the swim bladders of his captives with a tiny hypodermic needle. With luck, many of these prizes would be alive when they reached the aquariums at the Bishop Museum in Hawaii.

At 180 feet we met Peter and Rob where they relieved Bob and me of the cameras. Peter passed me the air bailout tank and I clipped it onto my harness. After completing a series of “deep stops” we followed the lengthy decompression schedule prescribed by our Vr3 computers and continued our slow ascent.

Three hours later we surface beneath the brilliant Fijian sun. Our deep diving protocol includes fifteen minutes of inactivity on the surface before climbing into the skiff. Michele threw me a mango. I pulled out my dive knife and pealed it while resting on the surface with my stabilizing jacket inflated. The sunlight was dazzling and a mango never tasted so sweet.

Note: Coral Reef Adventure will open in giant format theaters worldwide in February 2003. A schedule of screenings can be found in our IMAX® Theater Listings.