Back in the 1970s Lizard Island was a magnet for roughneck fishermen hunting black marlin - among them the American actor Lee Marvin, who made an annual pilgrimage here. Little remains of this colourful chapter in the island's history, although the resort still sponsors a marlin competition every October. The tourist interest is moving swiftly away from big-game machismo towards more eco aware interests including marine appreciation. From dawn to dusk pale-skinned Americans, immaculately dressed Italians and well-upholstered Aussies can be seen setting out to explore the Great Barrier Reef. Whether taking part in an organised dive or mounting their own expedition by motorised dinghy (picnic hampers are available on request), no part of the reef escapes their scrutiny. Curiously, the powdery white beaches are left largely undisturbed. Such is the lure of the coral and its exotic inhabitants that hardly anyone goes to the beach on Lizard Island. I was excited about exploring the island by foot as soon as possible. Like the beaches, the island's park-like interior (which includes rolling grassland, dense eucalyptus forest and mangrove swamp) is mostly deserted. I passed three people, all visiting yachties, the day I went for a hike. At 1,200ft, Cook's Look is the highest point on the island. I had the panoramic view to myself. It was from here that Captain James Cook charted a safe passage through treacherous reefs and out to open sea. A stone cairn marks the spot where the intrepid Yorkshireman stood on August 12, 1770. It's wondrous. He called the Great Barrier Reef ?the insane labyrinth'. For him the coral was like a sharp edged cage. Having already narrowly escaped wrecking his ship, Cook was not ready to risk a second disaster.



When he came here, it was by necessity; he stayed long enough only to find an escape route through the reef, replenish his stocks of fresh water and become acquainted with the island's population of monitor lizards. ?The only land animals we saw were lizards and these seem to be pretty plenty,' he wrote in his diary. Two centuries later the bowed-legged monitors are still a familiar sight. Despite their size and ugliness, the lizards are faintly comical. Beware if the critters as they have been known to bite. The diversity of species goes on and includes such members as geckos, skinks and even legless lizards. We've all met some of these on holiday. The diversity of birdlife on Lizard Island is incredible given the islands size. Unlike much of the Pacific, where birds tend to end up in the pot, you'll find 50 different species on Lizard, including the yellow-billed sunbird, the pheasant coucal, the sooty oystercatcher and the osprey. Bird Islet is a tern sanctuary. Away from the resort there is little evidence of previous human occupation, apart from a ruined stone cottage at Watson's Beach. It was here that Mary Watson, the wife of a Scottish sea captain, was attacked by Aboriginal islanders, the Dingaal, in 1881. With her husband away on a fishing trip, Mrs Watson - with her baby and Chinese servant - fled to sea in an iron boiler. All three drowned. This event seems to have ended the Dingaal's 10,000 - year occupation of Lizard Island, or Jiigurru. More recently their descendants have begun revisiting the island, and now advise the Queensland Parks and Wildlife Service on its conservation and management.

Today, Lizard's only full-time residents (apart from the resort staff) are a handful of marine biologists on the other side of the island. Run by the Australian Museum in Sydney, the research station attracts scientists from around the world. Even for a committed land-lubber, a tour of the research station was enough to produce a hankering for underwater exploration. I was intrigued by the reef's stranger inhabitants, such as gobys, tiny fish that can change sex at will. Sea cucumbers (or beche-de-mer) also became something of an obsession (the leopard sea-cucumber extrudes toxic poo). With 125 known varieties of sea cucumbers, it's time the producers of X-Men turned their attention to the ocean floor. The next morning I joined a snorkelling group to the inner reef. Like everything else on Lizard island, the trip was superbly organised and the reef itself magical and unspoilt. But an impromptu appearance by three humpback whales caught everyone on the hop. Battering into a heavy swell, our boat almost ran into them ? their tails majestically waving in the air. ?Let me assure you this does not happen every day,' said the captain. As a tourist, you get to enjoy more sights than the locals ever get to appreciate.' When the three 40ft whales began breaching, everyone wore the same gormless grin. A stunning display of synchronised swimming by the world's largest mammals but just another ?ooh, ah' moment on Lizard Island. The three blubbery extroverts finally went on their way and we returned to our own aquatic mission. After all, I had an appointment to keep with a toxic sea cucumber.