Twilight Zoneby Howard Hall |
We drifted over the reef edge near the mouth of the Tikehau Atoll pass. At one hundred feet, where the reef went completely vertical, we stopped to switch gases. The water below was dark, velvet-blue. Bob Cranston, Mark Thurlow and I turned off the air valve in our rebreathers, purged our low-pressure lines, and turned on our heliox tanks. We were breathing trimix as we resumed our descent.
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At one hundred and fifty feet Peter Kragh passed me the 250 lb IMAX® camera. With an 80cf tank of bailout air side-mounted on his rebreather harness, Peter found a comfortable position and held station as he watched us fall into the dark water below. We had two other bailout gases stashed on the reef above, one of 50/50 nitrox and the other of pure oxygen. Mark Thurlow carried an 80cf bailout tank filled with trimix and Bob and I each carried 30cf bailout tanks of trimix. If one of us had a malfunction, between the staged bottles and what we carried on-board there should be enough open circuit gas to complete the four-hour dive. But it was a theory I didn't wish to test.
At one hundred and ninety feet a wide shelf interrupted the vertical wall. There was a twenty-foot diameter hole in the shelf that went straight down. A dull glow emanated from the hole. We dropped into the hole and allowed ourselves to fall slowly toward the dim light. At two hundred and fifty feet a thirty-foot diameter aperture opened to the reef wall. But the vertical hole didn't stop there. It continued straight down and as my eyes adjusted to the darkness, I could see another glow very far below. How far down was that? Somehow the idea of descending further into that dark orifice, as the glowing LCD screen on my dive computer indicated 300 feet and beyond, failed to stimulate my need for adventure. I pressed the microphone button on my OTS comm. system and said, "Let's move out of here."
"Good idea," replied Mark.
We moved out through the cave opening and resumed our descent down the vertical wall. Despite the brilliant noontime sun, the light here was subdued. Unfamiliar monochromatic fish darted between dark recesses in the reef, their colors concealed by the filtration of 300 feet of seawater. My eyes struggled to focus on these ghost-like wraiths before they disappeared from view. It was a glooming world in perpetual shadow. Trimix divers call these depths "the Twilight Zone."
At 340 feet we discovered a second opening at the end of the vertical cave and it was enormous. From where I hovered near the upper lip of the opening I estimated the cave floor to be another seventy to one hundred feet below. There was no place to put my feet down. Hovering at 340 feet, I felt I needed to rest. The rapid descent left me feeling strange, unstable, and vulnerable. At these depths some deep divers experience helium jitters, but maybe I had hypercapnia - too much carbon dioxide. Whatever the cause, I didn't like it. I needed to stop here and rest for a minute. I hooked my fingers over a rock and hung from the upper lip of the cave and tried to breath evenly and deeply. The IMAX® camera was heavy at this depth. Deformed by the pressure, the housing had become about three pounds negative. It felt like the camera was pulling me down.
Nearly one hundred feet below where I hung from the cave ceiling, the cave floor spilled out to the reef, which then sloped away at about forty-five degrees. The water was amazingly clear despite the darkling light. The reef slope far below was covered with sugar-white sand that almost seemed to fluoresce light-blue light. And moving over the glowing blue sand was a school of more than one hundred gray reef sharks. I watched in amazement. I was observing marine life at nearly 450 feet! Nothing was stopping me from releasing my grip and drifting down into the school. Nothing but a strong sense of self-preservation.
After a minute or so hanging from the roof of the cave, I felt stronger. I moved the heavy camera away from the wall and swam out into the dark blue void carefully controlling my buoyancy. "I'll get a shot of you guys moving along the roof of the cave, OK?" I said, sounding like Donald Duck with marbles in his mouth. Bob and Mark acknowledged. About sixty feet away from the cave opening, I turned around and double-checked my depth - still 340 feet. I flipped on the camera power and video monitor. Then I took a light meter reading. With the ASA set at 1000, the meter read f-4 pointing up and f-1.6 pointing at the reef. I set the aperture at f-5.6 and depended upon the powerful Ikelite hand lights carried by Mark and Bob to provide a suitable exposure.
 "Howard drifts down the wall at 300 feet" - ©Bob Cranston |
"Action, action, action," I called into my microphone. I pressed the camera-run switch and heard the camera ramp up to speed. Bob and Mark began moving along the upper lip of the cave. From sixty feet away with a 180-degree wide-angle lens, they looked like tiny astronauts climbing across the face of an asteroid.
Ten seconds into the shot the camera began making a terrible squealing sound. At fifteen seconds the sound became a scream. Sixteen seconds into the shot the camera jammed. During the making of Coral Reef Adventure, we had made twenty-one deep trimix dives and performed more than sixty hours of total decompression. On more than half of those dives our IMAX® camera had failed to run. Ironically, we had discovered the reason for the failures and had finally corrected the problem for this, our last trimix dive of the production. But, as luck would have it, on this dive the camera jammed anyway due to a minor mistake when adjusting the magazine. After taking a moment to control my disappointment, I pressed the push-to-talk button on the microphone. "That's it guys, the camera jammed."
"We heard," Cranston replied tentatively. Mark and Bob could hear the camera screech from sixty feet away.
I turned the camera power off and moved back to the reef. Ascending to a small ledge at 320 feet, I paused to take a last look around. Mark and Bob continued move up past me. "You guys might want to stop here and take a last look. It could be a very long time before you're diving trimix at over 300 feet," I said.
Both Mark and Bob drifted down to the ledge and we paused together for a few moments to watch the sharks moving over the sand below 400 feet. We were all aware that our great adventure was coming to an end. This would be our last deep dive and last Coral Reef Adventure expedition. In forty-eight hours, after more than 170 days in the field spanning more than a year of production, the filming would be finished and we would be going home for the last time.
As we watched, the school of sharks moved into the cave below us. Dozens began circling up into the vertical shaft. A few moments later I saw sharks spilling out of the second opening seventy feet above us. What a shot that would be! Bob looked at me and I gestured to the jammed camera helplessly. Then he suddenly remembered the Nikonos camera he had clipped to his harness. Bob unclipped the camera and raised it to look through the viewfinder. Then he slowly lowered the camera and passed to me. The external viewfinder had shattered under the pressure at 340 feet and the shock wave had caused the internal viewfinder to shatter as well. Bob's camera was flooded. We turned and began moving up the reef.
Peter Kragh descended to two hundred feet, relieved me of the bulky IMAX® camera and passed me the air bailout tank. We ascended at a slow ten feet per minute while taking one or two-minute decompression stops every ten feet. Michele joined us at one hundred forty feet and began to photograph our ascent. By the time we reached fifty feet, our decompression stops were much longer. Michele was out of still film and Peter had passed the camera off to Mark Conlin and Betty Almogy. We sat on the reef, breathing slowly, and watched fish move in the deep blue waters beyond the reef. Our thoughts were peaceful as we contemplated the end of this memorable period in our lives.