By Bob Halstead
In Port Moresby in the early 1980’s I was hunting for derelict ships to sink as artificial reefs and dive sites. The biggest and most successful of these was the Pacific Gas. This was a 68m steel ship of 1,200 tons that carried two huge tanks of LPG. I coordinated its purchase by the PNG Government Department of the Environment and Conservation, and organized its sinking. The tanks were removed and the vessel cleaned. Pacific Towing donated a tugboat to tow it to Bootless Bay where we had an unofficial marine park. I purchased the explosives and Ian Short donated his expertise to set them off after placing them in key areas of the ship aiming for a controlled sinking without capsizing.
The ship was moored in the position I had chosen, spectator boats cleared, the explosives detonated and with in 12 minutes the Pacific Gas was on the bottom, upright, with its bow at 15 m and stern at 43 m. The wreck is in the lee of Horseshoe Reef and is fed by slight tidal currents that have ensured a healthy growth of corals since it went to the bottom in 1986 . It is an extraordinary dive and one made even more fabulous through its colonization by thousands of Flashlight fish.
Flashlight fish, Photoblepharon palpebratus, possess a light organ beneath their eyes that they can flash on and off at will. The light is produced by a symbiotic bacterium. They are a common fish in the Coral Sea area but hide deep in caves or shipwrecks during the day and can only be observed by diving at night, preferably on a very dark moonless night. I photographed my first one with Valerie Taylor as my dive buddy. We were in a coral labyrinth and she had advised me to turn my dive torch (flashlight) off once we had got into position, and just wait for the fish to appear. She had told me that if I got close to one in the dark and suddenly shone my light onto the fish then it would freeze, and I could get an easy photograph. It worked!
Recently I travelled with Captain Craig de Wit on his liveaboard dive boat, the adventurous Golden Dawn. We had made an expedition to explore the Coral Sea reefs out of Port Moresby and had returned to make our final dives. The Pacific Gas was to be our dive site for both an afternoon dive and a very special night dive.
Craig is a very experienced diver and a technical diving instructor. His was the first dive boat in PNG to offer Nitrox breathing gas, and he regularly offers re-breather courses and dives suitable for experienced divers. Our night dive, very carefully planned, was to be in this category. We were going to night dive – but without lights.
We moored to the wreck and the sea was calm. There was no current and no moon. We started gearing up at twilight with only dimmed saloon lights illuminating the dive deck. Our eyes were adjusting to the dark. The rules were simple. No camera flashes, no torches, no light sticks. If a diver insisted on taking a torch it must be turned off until the very end of the dive as even one light would ruin night vision for all of us. Dive times were strictly limited to ensure no one could run into decompression or low gas problems. We would navigate in close formation following the bioluminescence of the preceding diver. Craig would lead the dive.
Just as it got really dark we jumped in and followed Craig down the decent line. It was easier than I had anticipated. Bioluminescence sparkled as divers disturbed the plankton. Actually it was fabulous. We descended to the windowless bridge where we held on the outside, peering in to see Flashlight fish emerge. Their lights appeared to flash about every second but this could be because the fish were moving and thus the light organ would be obscured from moment to moment. They do not hold still but dart and turn continuously. I counted about twenty fish and thought, “This is cool!”
My eyes were getting well adjusted to the shades of black surrounding me, and I could make out the other divers both by their shading and by the trails of bioluminescence. Craig led off again heading for the bow at about 18m. At the briefing we had been told to hang on to the starboard bow and observe the opening to the anchor chain locker. As we settled, an eerie silver blue glow emanated from the round hatchway. We stayed perfectly still and breathed gently as a few lights appeared from the locker and flashed back again.
Then an incredible river of lights flowed from the opening. It was fantastic. I counted about ten lights a second and the river flowed and flowed for at least 5 minutes. Over three thousand Flashlight fish spread over the ship’s deck. The wreck glowed!
This was one of the most memorable and fabulous sights I have ever seen underwater. Awesome does not say enough. A miracle of nature is more like it.
Too soon, Craig called us for the ascent up the guideline to Golden Dawn and we stopped for a few minutes at 5 m. We were happy to hang and play sparklers with the plankton. It was a short dive, just 20 minutes bottom time, and we still had plenty of nitrox in our tanks – more than half, it turned out.
Every diver was ecstatic and on a post-dive high. All of us had followed Craig’s instructions and no one had any problems. Could we have done the dive with lights? Yes, but having our night vision unimpaired added enormously to the experience. Is it a dive for everyone? No, you need to be an experienced night diver, very comfortable in the dark and able to follow directions. I think the dive could have been much more difficult if there had been any current, but we had perfect conditions.
Diving by the light of the silvery moon may be romantic, but for sheer magic try diving by the light of thousands of Flashlight fish.