Night Diving on the Great Barrier Reef

I sit uncomfortably in inky blackness, trying not to fall onto Linton, who patiently bears my weight as I struggle to put on my fins. I'm the last one ready, and probably the most nervous, but I take a deep breath, let it out, and readjust my mask.
"Ready," I say. I put the regulator in my mouth and try to breathe through the tube that snakes to the tank on my back. It's heavy and trying to pull me backward into the water.
"One, two, three, GO!" someone yells, and I surrender to the tank, letting it pull me in. My flashlight points straight into the sky, before becoming obscured by the dark water. I do a flip and end up upright next to the dinghy, held afloat by my vest. There are six others with me, and we're at Bait Reef, an outer layer of the Great Barrier Reef off the Whitsunday Islands. It's my first night dive ever, and I try to control a part of me that's trying to panic. For the moment I succeed, and soon we're descending in invisible elevators into the void below us.
This is different than the experience I had earlier today, in the daylight. Now the water is obscured by tiny particles, like snowflakes that absorb the light. Earlier, the sunlight was caught by schools of hand-sized fish, throwing rainbows everywhere in a shower of prisms. The coral was only slightly blurred by the depth, giving it a dusty appearance: pale rose, chalky blue, smudged green. There were giant clams with pursed disapproving lips in neon colored patterns, like 80's clothing.
Now, the same trip is completely different. What we can see is only what we ourselves illuminate, and it has the appearance of a watery bone yard. The coral has gone pale, and looks like jumbled piles of deer antlers at one point, a huge brain at another. The fish are curious and follow us, using our flashlight beams to find their prey.
I struggle with staying on the bottom, and for a while I have to purposely swim toward the ocean floor, wasting energy and air that I'll want later. I finally realize my vest still has air in it. Once I release it, I sink to within inches of the coral for a better view.
We wander through a chasm between the coral columns, and I am under a dark shelf. When I look up, the coral beckons, pulsating, trying to capture food brought toward it on the current. I know it makes a noise, I can tell, but all I can hear is the sound of my own raspy breathing. It comforts me, because it means that I am alive and this isn't a dream. I am underwater in the darkness of the Great Barrier Reef.
Even though I'm more comfortable now, my initial panic uses up my air, and I have to surface with my buddy before the rest of the group. We look up, and the water is lit above us; you can see our air bubbles illuminated from the flashlights below, and from another source of light above them in the dark night. When I clear the surface, I am looking right into the source: a golden honey-colored moon has just risen, right behind the masts of a sailboat. I look straight up into a smattering of stars, and around me to the lights of the other boats on their moorings. When I look down again, I'm over the coral, and it glows in the moonlight, beckoning me, waving in the current.
I let a whoop, and my salty lips stretch into a smile that takes up my whole face. My after-dive euphoria is the only buoyancy I need, and I will float on it for years to come.