There's a shark swimming awfully near. It's eyeing me and I'm keeping a very close eye on it.
From 10 metres below the ocean's surface on the outer Great Barrier Reef, it's a long way back to the dive boat. Mentally I prepare to counter-charge. That's the instruction from our dive leader. If a shark charges, you go for it. The theory is it will be the more frightened and shoo off. Psychologically, this is a challenge and, while I'm contemplating this latest scenario, the whitetip reef shark disappears.
This small and rarely dangerous shark is common in these waters and certainly more alarming through family association than it actually is. What truly scares me this morning, is the state of the coral on the reef. Large tracts of staghorn coral beds lie dead and crumbling like rubble on a building demolition site.
I'm worried because during more than 30 years of diving at the Great Barrier Reef and seeing the destruction caused as the crown-of-thorns munches its way around, I have never seen anything as bad as this. Considered one of the top 10 dive spots in the world, the Cod Hole is in a sorry state.
When I surface at the end of the dive 50 minutes later, I learn that the mess was caused by Cyclone Yasi, which passed through the area two years ago.
Coral reefs take hundreds of years to grow, but I feel slightly relieved. A few years ago, I saw similarly damaged coral in the Maldives. That coral died as the result of an increase in sea temperature, which seems more permanent than this trouble closer to home.
The Cod Hole deserves its international status. Lurking sharks anddamaged coral cannot upstage the main attraction, giant tame potato cod. This creamy-grey fish gets its name from the large, black dots on its body the size of potatoes.
Lying about 250 kilometres north of Cairns and 30 kilometres from the coast of North Queensland, the dive site is almost on our doorstep. Finding similar quality, particularly a chance to swim alongside such big fish, would involve travelling to distant and remote parts of the world. Once before, I dived with super-large versions of this fish on the wreck of the Yongala off Townsville, but there you don't get close enough to appreciate the phenomenal size the species grows to.
Today, only one of the potato cod living in the area is appearing for photographs and raw fish, which it is fed by hand. I resist an urge to reach out and touch it, but when I go back later for a quiet look on my own, it the big boy actually bunts me.
As we continue our dive nearby, we see a few camera-shy versions of the oversized native grouper called the camouflage cod. They are equally awesome, although less willing to be involved in tourism than their relative. The giant cod is an endangered species and, at the Cod Hole, the average number seen during a dive has dropped from 12 in 1993-94 to less than seven today.
After lunch we move to a nearby reef called No Name, where the emphasis switches to small but amazingly colourful fish and sea life. Pink lace coral, yellow damsels, red bass and green turtles only hint at the colour spectrum just a few metres below the water's surface.
There are more than 1500 species of tropical fish on the Great Barrier Reef and there is not a tint or pattern that nature has not found to enhance the dazzling array in this section. The fleshy lips of the giant clams in iridescent greens, blues and purple are my favourites.
While most passengers on the day trip from Lizard Island are scuba divers, No Name reef is equally enjoyable for those wanting to view it using snorkel gear.
The finale to a full-day dive excursion comes at the end of the 50-minute fast boat ride back to Lizard Island, when diverse fish come to the back of the boat. As soon as the engines cut, two lithe, tawny nurse sharks raise their heads onto the aft deck to grab a feed of fresh fish.
Nearby are a couple of more groupers. These super-sized fish can grow up to three metres long and weigh up to 150 kilograms. I try to find them again later by snorkelling from the beach, but don't have any luck. Given their lifespan of 50 years, however, there is every chance they will be there next time I visit.
The Cod Hole and No Name Reef dives can be accessed on a day trip from Lizard Island for $395 a person, including all dive gear and lunch. Rooms at Lizard Island Resort start at $1699 a room a night twin share, including all meals and some drinks.
Mike Ball Dive Expeditions has three-night dive packages from Cairns from $1693 a person. See mikeball.com
Spirit of Freedom has three-day, three-night excursions from Cairns from $1550 a person, see spiritoffreedom.com.au
The writer travelled at her own expense.
FIVE RARE DIVES
Witness amazing fish action when large schools of red snapper, humphead parrotfish, Moorish idols and others congregate to spawn. Add the bonus of predators looking for an easy meal. visit-palau.com
Sipadan Island, Sabah, East Malaysia
Diving's answer to a horror film, a dive at Barracuda Point places you in the middle of thick streams of menacing barracuda. The thrill is enhanced by lurking hammerhead sharks and stingrays. sabahtourism.com
SS President Coolidge, Vanuatu
During World War II, this luxury liner was turned into a troop carrier, which sank after running into a minefield near the island of Espiritu Santo. The 198-metre wreck, with its Jeeps, chandeliers, cannons and mosaic fountains is just a few metres offshore and in excellent condition. vanuatu.travel
Great Blue Hole, Belize
A vast underwater sinkhole formed during the last Ice Age, the beauty here is in the karst limestone formations and multi-coloured stalactites and stalagmites. The 300-metre-wide, 124-metre-deep hole is also home to giant groupers. travelbelize.org
Sha'ab Rumi South, Sudan
Diving in the Red Sea is truly unique. The visibility is excellent and out of Sudan very well preserved. Jacques Cousteau's 1963 research base is still here, as is a grey reef shark cleaning station, where other fish spruce up the marine monsters. sudtourism.com