Not a whole lot actually happens in the book: the author mostly fails to cover the marathon, stays in a house by the sea in bad weather, goes fishing a couple of times, and that's it. But Thompson, as ever, like a 20th-century Laurence Sterne, manages to spin this meagre material into a hilarious grand farce filled with rich descriptions and unlikely digressions, fraught with peril and involving a cast of dangerous oddballs with whom he has deeply strange and funny conversations. Throughout, the usual Thompson chaos of alcohol and drugs, casual violence and massive overspending on other people's tabs prevails.

Originally published in 1983, the book was withdrawn from sale soon afterwards, then re-released in 2005 by boutique publisher Taschen in a limited-edition of 1,000 predictably lavish (for which read: expensive) hardback monsters, each of them signed by both author and artist; Thompson took his own life just a month after it was published.

It has now been reissued by Taschen in a smaller, more affordable but still handsomely produced hardback version. "I prefer it to the bigger one, which looks like a comic book," says Steadman. "Now it looks serious again. I can't believe it when I look at the pieces in there and see '81 on them. It feels like someone's stolen about 25 years of my life."

In a prolific career lasting nearly half a century, Steadman has become instantly recognisable, particularly in his native Britain, for his trademark sharp, satirical, often grotesque drawings of politicians, public figures and others; they have graced the pages of more or less every newspaper and magazine of note there. He has also provided the art for a range of canonical classics, including , and , and has created everything from children's books to film posters to product packaging (including a wine label banned in Ohio for religious reasons).

His work is full of savage humour, but serious intentions are never far from the surface: , for example, is a book featuring his drawings of species of birds no longer with us; he's currently working on the follow-up, , featuring birds that are critically endangered. He's even the subject of a recent feature-length documentary, - that was Thompson's usual explanation, he says, if he asked why they were doing something.

But it was his work early in his career with Thompson that first brought him to wider attention. They were an unusual pairing, apparently incompatible in most respects except the artistic: Steadman hates sport and doesn't take drugs; Thompson was addicted to both. They met when they worked together on 1970's splendidly titled , the article that marked Thompson's new journalistic style, known as gonzo, in which the supposed subject matter plays second fiddle to the shenanigans of the writer.

Steadman also illustrated the writer's two best-known works: 1971's and 1973's . Steadman says former US president Richard Nixon, who features heavily in the latter, has been his favourite subject to draw, "because he was so evil, and because his nose was like this wonderful ski jump".

, however, was their closest collaboration. Steadman accompanied Thompson for large stretches of the trip, gets a joint author credit, and even came up with the title; Thompson wanted to use the rather more prosaic . As a result, there are numerous Steadman drawings throughout the book and they show him at his most diverse: Thompson appears in full-on Raoul Duke mode, complete with aviators, cigarette holder and bucket hat, but alongside and often blended cleverly with local scenes and motifs from Hawaiian culture. Duke is the fictional anti-hero and narrator of several Thompson stories.

There are also several depictions, from sparse black-and-white line drawings to a doctored version of a classic painting, of explorer Captain James Cook, believed by some locals when he visited the islands to be a reincarnation of Lono, held in myth to have left the island in a magical canoe. Thompson, when he lands a giant marlin after a series of failed fishing trips, falls prey to the same delusion regarding himself, as a result of which the local people threaten to drum him out of town and he ends up fleeing to traditional sanctuary the City of Refuge.

"What captivated Hunter more than anything was the idea of Lono going off in a canoe," Steadman says. "It was the sort of freedom he wished he had himself."

In fact, Thompson had begun to pick up enemies on the trip long before that, starting at the airport when they arrive thanks to his friend Gene Skinner, one of the book's range of deeply alarming characters, who yells "Stand aside! Do you want to be killed?" at a small child who gets in his way, following this up on the journey from the airport by killing a stray dog with a blow to the head delivered with a beer bottle from a moving car, and then announcing that "It's time to break out the drugs. I feel nervous."

The group's unpopularity increases when, as Steadman recalls amid a fit of convulsive chuckling, he, Thompson and their retinue cover the marathon by setting up chairs near the end, drinking heavily and abusing the competitors, safe in the knowledge that they're unlikely to stop and argue. "Run faster, you lazy bastards," guffaws Steadman, slipping into a pitch-perfect impersonation of Thompson's trademark growl.

Throughout their collaborations, says Steadman, he himself also caused plenty of offence, mainly because the sketches he drew of people in front of them were so warped, distorted and grotesque. In fact, people have the wrong impression of him from his work, he adds. "People say to me: 'I thought you'd be horrible.' But all that anger, I get it all out on paper, and I'm actually pretty well adjusted.

"People say to me: 'Do you do your drawings in pencil first and then go over them? What if you make a mistake?' But there's no such thing as a mistake. It's an opportunity to do something different. That to me is what creativity is. You've got to start somewhere, so I just start.

"Pencilling in and then going over? No wonder some drawings look half-dead."

Steadman himself is just one of many characters played to comic effect in . Thompson spikes the cartoonist with a vast quantity of sedative valerian root, then takes him on a fishing trip where "they put a gigantic rod and reel in his hands and told him to hang on, because the bait he was trailing would be swallowed up at any moment by a fish the size of a bull moose, which would then erupt from the deep like a missile and 'take off across the top of the water at seventy miles an hour'".

Thompson builds an aura of menace in the book, the threat of danger and violence never far from the surface, the islands themselves portrayed as a dangerous place, a seething mass of racial tension and casual violence fed by isolation and tropical weather. The possibility of imminent catastrophe reaches its apogee on an overnight fishing trip in the company of the dissolute Captain Steve and even more dissolute first mate Ackerman, who ends up sniffing heroin, almost the only intoxicant Thompson doesn't like. "'A lot of times it's the only way to keep from killing the clients.' I nodded, pondering the long night ahead. If the first mate routinely snorted smack at the cocktail hour, what was the captain into?"

The follow-up fishing trip during which Thompson lands the marlin and gets delusions of godliness is told in a letter to Steadman, who had returned home by then, the moment captured in the book's only photo, in which he stands next to the fish hefting the Samoan war club he'd beaten it to death with.

"He loved that club," says Steadman. "It became important to him. I have photos of him in Washington swinging it about and shouting about something - I've no idea what. Within great intelligence, there's always strange weirdness and sometimes also cruelty. I know he was crazy. But people say, 'Was he unkind?' and he never was."

The book's climactic moment is also illustrated with a drawing of Thompson hanging up by his feet. "I'm looking now at that image of Hunter as a fish," says Steadman. "That was me getting back at him. A good working relationship should have that creative anger. I think we kicked each other's butts."