Rare glimpse of a vanishing world

DESPITE THE EFFORTS BEING MADE to save the environment, today's divers may be among the last to see many of this planet's most fascinating creatures alive.
In the words of cameraman Pawel Achtel, "encountering rare wildlife often feels like a farewell". All that will be left for our children are our recordings.
I meet Pawel and my photographer, marine biologist Justin Gilligan, in the tourist mecca of tropical Cairns. Pawel has chartered Kalinda out of Townsville for a film-making trip to the far north.
The vessel, skippered by marine scientist Dave Stewart, caters for clients who want to explore outside the commonly dived sites of the Great Barrier Reef. For this expedition, Pawel has invited a few paying passengers.
With provisions for a fortnight away from civilisation, we leave the holiday resorts in our wake. Raine Island and the Great Detached Reefs are in a very remote location. In fact, the area is still largely uncharted.
Officially, these reefs are part of the Great Barrier Reef. Ecologically, they're something else. Located outside the continental shelf, where extremely deep waters meet the relative shallows of the GBR, this reef system hosts not only the GBR's rather coastal fauna but also pelagic species usually associated with Coral Sea atolls.
Scientists speculate whether strong tidal currents and an upwelling of nutrient-rich deep-sea water contribute to the special ecology here. Whatever the reason, the result is quite exceptional diving conditions.

OUR FIRST DESTINATION is Stapleton Island, where Pawel plans to photograph green turtles feeding. It's a couple of days' steam, and as we cruise north, he keeps his camera and a rebreather set up on the dive deck for any eventuality, such as baitballs.
Anything could happen in these waters. Recently, a large Spanish mackerel jumped clear out of the ocean and landed some 3.5m up on the canopy of a boat here. What was chasing it?
We reach the island for an early-morning dive. Pawel's gear makes you wonder whether there's a war on; his closed-circuit oxygen rebreather is an impressive bit of restricted-issue military kit. It's extremely compact, black and camouflage-patterned, and apparently gives off less acoustic echo than a fish - very handy when you're filming shy wildlife.
The drawback, naturally, is that because of O2 toxicity under pressure, you can use it only down to 6m.
Pawel's camera gear is equally imposing. In a custom-built stainless steel and titanium housing, he keeps a cinema-grade camera, a Sony HDCAM.
Powerful halogen lights are mounted on long arms to the sides and, for absolute control under water, a BC is mounted on top.
It's the sort of camera that, when pointed in your direction, makes you feel famous.
Rebreather or not, the turtles are having none of it. We see plenty from the tender, but as soon as we're in the water, they're gone. It's the middle of the turtle-nesting season, a bonanza for predators, and from the turtles' point of view anything big and bulky could be a tiger shark thinking about lunch.
They are especially wary in the shallows, where they have less room to navigate, so filming them is more difficult than expected.
We have to hope to get turtles at Raine Island, where they usually rest on shelves along the drop-offs.
Next stop is a sand cay, where we step ashore for Pawel to do time-lapse photography of the sunset. The dunes are packed with brown boobies and sooty terns. Watching us with their reptile eyes, they let us come right up to them.
Their lack of fear is testament to how seldom they have contact with humans, and highlights one of the main challenges of conservational work.
How are people to know what to protect when they have never seen it? Out of sight, out of mind.
It's a problem that is even more evident in the underwater world, which few people ever see with their own eyes. Coral reefs are disappearing twice as fast as the rainforests.
The remedy, of course, is education through mass media, and Pawel intends to contribute with a full-length documentary on Australian marine life for cinema. He's hoping for a result akin to that of Jean-Michel Cousteau's feature on the Hawaiian Islands, which led to the creation of the world's largest marine park. As the sun sets on the busy seabird colony, he adds a few thousand frames to the project.
Working our way up to Raine Island, we enjoy one great dive after another. The reefs are characterised by sheer walls covered in soft and hard corals, gorgonian fans and sponges, and a huge diversity of fish, great and small.
Visibility usually ranges from 30-60m, but a cyclone has recently passed, so on some sites we have to make do with around 20.
A surprising number of baby silvertip as well as young whitetip and grey reef sharks join us on many dives, and occasionally chunky adults check us out before going back to patrolling the reef edge. The frequent shark sightings are a reminder that the Coral Sea, sadly, is one of the world's last strongholds of sharks. We encounter seven species on this trip.
Slowly finning along the drop-offs, we make a habit of looking into the blue every now and then. Many of the dive sites are situated next to abyssal depths of 600m or more, and you never know what might emerge.
At Tijou Reef, I'm thinking just that when a huge dogtooth tuna suddenly races past. Together with the sharks, barracuda and Spanish mackerel, these silvery tanks keep all the little reef fish on their toes - or fins. This is a highly active eco-system, a battle zone.

ECOLOGY ISN'T THE SOLE DRAMA, however. We plough the waters of Wreck Bay. At least 21 vessels sank in the area during the 18th and 19th centuries. Only three have been located. One is HMS Pandora, the ship sent from England to capture the mutineers from Captain Bligh's HMS Bounty. With a few prisoners still in a holding pen, she went down north of Raine Island in 1791.
At an unnamed solitary bommie, we get a feel for what the shipwrecked sailors must have experienced. There's little to see but the vast expanse of ocean and the turquoise speck of the bommie. Not a vessel has been sighted for days, and there are no birds in the sky. We're alone.
It's a curious situation. Above the surface, the ocean is a desert. Below, it's an Eden. Like a fairy-tale tower, the bommie rises from the bottom at 120m or more, its walls covered in soft corals, sponges and gorgonian fans, with caverns opening up like windows.
Wide-eyed and colourful inhabitants peer out from the darkness. There's little parking space left for any more life-forms. It's what scientists call a hotspot, an area of extraordinarily high biodiversity. These reefs are near the renowned Coral Triangle, the region with the greatest number of coral species in the world.
With a summit at 16m, the bommie isn't marked on the charts, and had it not been for the experience of the Kalinda crew, we wouldn't have found it. It's probably never been dived. You can tell by the pristine coral - and by the way the sharks look at you. It's wild.

DUE TO REMOTENESS and usually rough weather, Raine Island and the Great Detached Reefs are visited by only two regular tourist boats, for a few weeks of the year. This makes for a different kind of diving than that at popular sites further south, and at Mantis Reef we find out exactly how different.
Pawel, Justin and I have just gone in when Pawel realises that he's low on camera batteries, and surfaces.
Now it's only Justin, me and the ocean. The other divers won't be entering for another 30 minutes.
We drift along a drop-off. Every now and then, sharks cruise by to investigate. A school of barracuda hangs about. Sponges and soft corals punctuate the reef wall with splashes of colour.
Flowery cods shoot out from crevices here and there, while the damsels and anthias stick to their coral homes.
It's a pretty normal dive, yet something doesn't feel right. A dark shape looms at the edge of our field of vision. We are being followed.
All of a sudden, a bulky silvertip shark rocks up and starts to show a lot more than curiosity. It makes pass after pass at us. I don't take it too seriously until Justin, the marine biologist, signals for me to stay close. This means trouble.
With the shark making bolder and bolder moves on us, I eventually get my gear off and hold it out in front of me like a battering ram. It's very tense. There's no telling when the shark will attempt a bite.
To our relief, the shark disappears after a number of close passes. We figure that it will stay at depth, and we ascend a bit to continue the dive. We even joke about the incident. Then the shark returns. At around 10m, it starts to make increasingly worrying approaches.
Sharks aren't supposed to do this to divers. They're supposed to show off their beauty and get intimidated when you try to get closer to take their photo. They're not supposed to treat us as if we're part of the food chain.
My gear comes off again, and I free-flow my two spare regs. It doesn't seem to impress the shark, nor does shouting or staring it down. It's time to leave.
Sticking like glue to the reef wall, we basically climb the last 8m to the shallows of the reef-flat. We surface hundreds of metres from Kalinda, and can do little but inflate our safety sausages and hope that the shark stays off the wall. Luckily, it does. This is wild enough for us.
For all the marvellous - and adventurous - diving we enjoy on the way north, Raine Island stays in the back of our minds. This sand cay hosts the planet's largest-known rookery for the endangered green turtle; between 14,000 and 22,000 have been recorded on one night in the breeding season, which lasts from November through January.
It's also the most important seabird sanctuary in the Great Barrier Reef Marine Park, with 84 species recorded, including 16 breeding.
And tropical Australia's oldest European building tops it all off. The Raine Island beacon, built by convicts in 1844, can be seen from miles away.
In the binoculars at the crack of dawn we see the beacon surrounded by a cloud of seabirds, the heavy breakers off the island painted gold by the rising sun.
A pod of bottlenose dolphins is escorting us, as frigate birds and boobies level out by the wheelhouse before flying off to dive-bomb a school of baitfish in the distance. It's a grand welcome.
Tens of thousands of tonnes of guano were mined here in the early 1890s. Kitting up downwind from the island, we can tell that the stocks have been replenished since the mining ceased. Today, Raine Island affords full protection as a marine sanctuary.
Entering the water, we soon come upon several large green turtles. One has lost a big chunk from a front flipper; the turtle-breeding colony here has a loyal following among tiger sharks.
Mapping of the movements of tigers fitted with GPS tags suggests that they are basically in orbit around the island. They are not likely to miss out on the easy pickings provided by turtles worn out by digging and egg-laying.
The topography varies from plateaus that form steps into the blue to sheer drop-offs plunging to 40-50m.
In the company of silvertip sharks, numerous whitetip and grey reef sharks cruise up and down the reef, while a coral-munching school of humphead parrotfish is hard at work, creating future sandy beaches.
A bull ray spreads out like a rug on the seafloor. An epaulette shark peeks out of a crevice, and a large tawny nurse shark suddenly emerges from a cave and slowly swims off into the deep. Giant oceanic jellyfish hover like UFOs. It's a lively menagerie.

AFTER A DAY'S DIVING at Raine Island, we head back towards Cairns. Pawel wants to capture some footage of nesting turtles at Sandbank 7, further south. This is a protected nature reserve, and only a select few scientists and film-makers are allowed to step ashore. It should provide excellent photo ops.
We arrive in the afternoon. From our mooring, we can see what look like tank tracks running at right angles up the beach. The turtle-nesting is apparently well under way.
Making landfall and lugging loads of camera gear, we discover the remains of several turtles. Flaking carapaces and whitening skulls dot the dunes. Digging and egg-laying are arduous tasks, and studies on Raine Island have shown that about 5% of nesting turtles perish in the process. They come on land in the cool of night, and if they're not back in the water by sunrise, they run the risk of being cooked alive.
We're lucky enough to witness the success of one massive female that slowly pushes herself up the beach and starts digging out an egg chamber.
She's slow but relentless, toiling for hours in front of Pawel's cameras. It's early morning before she finishes and labours her way back into the sea.
In one exceptional nesting season, the number of turtles visiting Raine Island and nearby Moulter Cay alone was estimated at more than 103,000. That's
a lot of turtles, and they're relatively safe here. But as they migrate into the domains of Indonesia, Papua New Guinea and Solomon Islands, Australian legislation can't protect them any more.
The green turtle is named for the colour of the fat inside its shell, and turtle meat is a highly sought after traditional food in many places.
Generations to come may well find it overwhelming to see that single turtle nesting on the beach. We have very mixed feelings when Sandbank 7 recedes in our wake the following morning.
A couple of days later, we're back at the Northern Ribbon Reefs, and Pawel decides to finish the expedition with a dive at the famous Cod Hole. Its stars, the gigantic potato cods, are usually very friendly and inquisitive, and today they have something special in store for us.
As they swim around like playful pups, a couple of them start behaving in an odd way. They are courting - right in front of Pawel's camera.
The couple swim close together, tenderly nudging and stroking each other. It's an intricate dance, an example of the complex underwater worlds that we are only beginning to understand. Scenes like this are exactly what we need to convince people to protect the ocean.
We hope the footage will find its way into the hearts of voters and politicians, so that future generations can see the wonders of Australian marine life. Pawel keeps his camera rolling, the last few frames of the expedition registering the love of two iconic fishes.