As I made my descent into the city of Cairns, in Queensland, northern Australia, like everyone else on the plane, I craned my neck to get a view of the Great Barrier Reef. It’s a pretty remarkable sight even from this perspective.The Great Barrier Reef is the largest structure on earth created by living things. It stretches over 1,200 miles, and supposedly, even if I had been looking out the window of the space shuttle it would have been visible from space.
Of course the best way to experience the reef is from underwater, but a trip out on one of the many livaboard boats that operate here does not come cheap. After a few days walking the docks and asking around, I managed get a standby fare when someone cancelled aboard the ship Taka. I only had a couple of hours to pack before the ship set out for a five-day trip to the outer sections of the coral sea. I had just enough time to throw my things together and rent an underwater housing for my camera.
As the boat pulled out and I started to assemble some of my dive equipment, despite stormy weather and ten foot swells, I was happy as a pig in muck. I learned to SCUBA dive in Burlington VT, in the cold of winter. It was often so cold that we would rent a UHAUL truck, park it on shore with a space heater in the back, and bolt strait into it after each dive. On some days we would have to waddle out along the ice with our tanks and fins, just to reach the slightly less frozen, frigged waters. Visibility ranged from five feet, to five inches in front of our faces, depending on how much silt got kicked up by divers loosing control of their buoyancy and churning up the murky floor. As far as things to see, Lake Champlain, where we did the majority of our dives, boasts such underwater wonders as several discarded dinner plates from the dinning service of the old Plattsburg ferry, a surprising number of shopping carts, and at least one toilet. Despite the lack of life down there, I came to love the experience. Even during our pool training I enjoyed the sensation of being underwater for prolonged periods of time. 
I remember the excitement of my first dive, when I turned upside-down and saw the light refracting on the surface. I watched as my bubbles floated up towards the light and I realized for the first time that I didn't have to make a dash up there for air. Just the feeling of weightlessness, being able to hover suspended in space, rising and falling slightly with each breath - it is one of those truly amazing experiences. Then of course there is the underwater world to explore.
As the boat pulled out and I started to assemble some of my dive equipment, despite stormy weather and ten foot swells, I was happy as a pig in muck. I learned to SCUBA dive in Burlington VT, in the cold of winter. It was often so cold that we would rent a UHAUL truck, park it on shore with a space heater in the back, and bolt strait into it after each dive. On some days we would have to waddle out along the ice with our tanks and fins, just to reach the slightly less frozen, frigged waters. Visibility ranged from five feet, to five inches in front of our faces, depending on how much silt got kicked up by divers loosing control of their buoyancy and churning up the murky floor. As far as things to see, Lake Champlain, where we did the majority of our dives, boasts such underwater wonders as several discarded dinner plates from the dinning service of the old Plattsburg ferry, a surprising number of shopping carts, and at least one toilet. Despite the lack of life down there, I came to love the experience. Even during our pool training I enjoyed the sensation of being underwater for prolonged periods of time. I remember the excitement of my first dive, when I turned upside-down and saw the light refracting on the surface. I watched as my bubbles floated up towards the light and I realized for the first time that I didn't have to make a dash up there for air. Just the feeling of weightlessness, being able to hover suspended in space, rising and falling slightly with each breath - it is one of those truly amazing experiences. Then of course there is the underwater world to explore.
The first time you descend into the alien world of a coral reef, teeming with life and bursting with color, some people find it reminiscent of the closest environment on land, a tropical rainforest. Flowing coral fans and the jagged branches of staghorn conjure up a vibrant jungle canopy. 
Instead of flowers, soft corals and anemones with their bright tentacles sway with every surge. Urchins, starfish, sea cucumbers, tiny crabs and tinier shrimp, crawl and pick over everything.Then of course there is the kaleidoscope of fish, they seem to take the place of tropical birds, and dart in and out of every crevice, or swarm together in massive schools. In fact coral reefs outdo rain forests in terms of biodiversity, and hold the world's record for densest and most complex concentration of life on earth.
On board Taka, we did twelve dives, diving around the clock. Even at night the reef is crawling with life. We did several night dives where only the beam of our torches penetrated a pitch black sea to reveal a whole different range of creatures. The highlight for me was when doing an early morning dive, right at dawn I found where a hawksbill turtle had slept, wedging its body under an overhang of coral outcrop. It slowly emerged and I followed it up as it glided to the surface for its first breath of the new day.
When not diving I sat in the ships lounge reading “Coral Reefs: Cities Under the Sea” by Richard C. Murphy. It’s a bit of a strange book - part marine science, part science fiction. The author draws insight from the relationship between different organisms within the reef and the way they collectively create an efficient system. In the “coral city” that the author describes there is no waste. The by-product of each organism is the resource for the next. Taking the reef's example, he considers how our own cities might better manage things like energy, resource management and waste removal. He also gives an interesting explanation of what the reef itself is.
What we call the reef is really a symbiosis of two organisms, one a plant and the other an animal. The animal is called a polyp, and the plant is an algae called zooxanthellae. The polyps actually evolved from a common ancestor of modern jelly fish. Its physical structure is basically that of a jelly fish that has rejected the strategy of floating with currents and capturing prey in the open ocean, and has anchored itself upside-down waiting for prey to come to it instead. These polyps have managed to form a unique relationship with algae cells, which is mutually beneficial to both species. 
The zooxanthelae use sunlight to produce food which they share with the colony of polyps. In return the polyps form a structure which provides the algae with shelter and access to more sunlight. Many polyps are also capable of preying on other drifting animals called plankton. The by-product of this type of feeding is shared with the algae giving it the nutrients it needs to grow.
The giant reefs systems we see today are a result of countless generations of these coral colonies piling up layer upon layer of calcium carbonate over millions of years. The hard part of the reef is really the shared skeletons of large colonies of polyps. The living part of coral is only on the surface. Many reef species specialize in feeding off this thin layer, like this parrot fish which uses its beak like teeth to break pieces of the reef off and extracts the algae cells inside. Although this destroys small portions of the reef, it is actually a necessary process in reef growth, as new coral colonies can only get their start on these bare patches. 
Individual coral colonies can grow in size and number through cell division, and each polyp in a colony is an exact clone of other members. However, new coral colonies only form once a year, on a single night, usually two to seven days after the full moon of mid-summer, when a simultaneous mass spawning fills the reef with a sea of coral larva.When you look at a large patch of coral you can see the separate species living on top of one another and guess where the founding polyp landed to form each individual colony.
For our final dive we motored into a section of reef closer to Cairns, and civilization. We usually had a dive briefing before each dive, where the layout of the reef was described as well as the types of life we could expect to see. On this last one, the ship’s dive master said it was just a “free dive” and that we should just explore it on our own.
After four days of basking in the explosion of life and color surrounding the outer sections of pristine reef, we descended into a coral graveyard. There are few sights in this world as depressing as a devastated section of coral reef. The bombed-out look of this sick section of coral was a complete shock. Some coral was bare and a ghastly bone white. Other sections were covered with a kind of brownish scum. Without the constant filtration that a healthy reef performs, the water had turned thick and murky, adding to the gloom. A few fish clung on, hiding in the shadows of the rubble of broken coral. It was quiet and lonely down there and difficult to have a full tank’s worth of air to consider what we were seeing.
When I surfaced and pulled myself up on deck it was quiet. After each dive over the last few days, the gear deck, where we took off our equipment and refilled our tanks, had been the scene of a festive and lively swap of accounts of the various creatures divers had spotted. It’s a time when the diver's excitement bursts out everywhere. After having been restricted to communicating through limited hand-signals, now they can finally tell their dive buddy how amazing that big shark was or find out if anyone else saw that tiny seahorse. After this dive however, it was as solemn as a funeral. When a couple of divers made some complaining remarks about the quality of the dive, the dive master made some appropriate comments about the importance of people getting to see this part of the reef too.
After four days of basking in the explosion of life and color surrounding the outer sections of pristine reef, we descended into a coral graveyard. There are few sights in this world as depressing as a devastated section of coral reef. The bombed-out look of this sick section of coral was a complete shock. Some coral was bare and a ghastly bone white. Other sections were covered with a kind of brownish scum. Without the constant filtration that a healthy reef performs, the water had turned thick and murky, adding to the gloom. A few fish clung on, hiding in the shadows of the rubble of broken coral. It was quiet and lonely down there and difficult to have a full tank’s worth of air to consider what we were seeing.When I surfaced and pulled myself up on deck it was quiet. After each dive over the last few days, the gear deck, where we took off our equipment and refilled our tanks, had been the scene of a festive and lively swap of accounts of the various creatures divers had spotted. It’s a time when the diver's excitement bursts out everywhere. After having been restricted to communicating through limited hand-signals, now they can finally tell their dive buddy how amazing that big shark was or find out if anyone else saw that tiny seahorse. After this dive however, it was as solemn as a funeral. When a couple of divers made some complaining remarks about the quality of the dive, the dive master made some appropriate comments about the importance of people getting to see this part of the reef too.
