About once every four or five years, an erudite, self-deprecating and half-mad natural historian from Oxford launches into one of the world's wildernesses. The result - a new book by Redmond O'Hanlon - is always something to look forward to. We have been treated to mosquito hell in Borneo, hallucinogenic trips in the Amazon and searches for long-lost dinosaurs in the Congo. Now O'Hanlon has explored somewhere just as fascinating, and much closer to home: the far reaches of sanity.
His new book is set on a North Atlantic trawler sailing out of the Orkneys. For reasons never entirely clear, he befriends a doctoral student of marine biology at Aberdeen, Luke, whose field studies involve sailing the Arctic waters in a Force 12 mini-hurricane. Only one captain, Jason, is crazy enough to trawl in these conditions, and he does so because he has racked up £2m of debt. Only one writer is crazy enough to go: O'Hanlon.
Many of the deft touches which grace O'Hanlon's books are here. His passion for wildlife centres on the species of the ocean deep, while his comic timing highlights his relationship with the trawlermen, who call him Worzel. The passages where he describes the love of the first mate for his wife, or the disappointment of a trawlermen at being let out of jail (a soft touch compared to the North Atlantic), are written with great affection and admiration.
None the less, this book is very different to previous offerings. Jason is taking the trawler to new fishing grounds, and O'Hanlon is not allowed to reveal their exact destination. So in place of a traditional travel narrative the book becomes a jumble of argument, ideas and descriptions of strange fish.
That this phantasmagoria is best suited to the material becomes clear when we learn that trawlermen sleep just one hour in every 24 at sea. As sleep deprivation increases, reason is blustered into thin air. Capsize and death are a failed motor away; bankruptcy looms. A measured emotional atmosphere, conveyed by crisp descriptions of scenery interspersed with conversations, is no longer appropriate. Everything collapses into expletives, tear-jerking friendships, sexual neurosis, fear, mortality.
This experience gives O'Hanlon an opportunity to explore his craft, which he does with great skill to show that the best travel books are empty vessels for the writer to fill. Sensing an opportunity to assess the great problems of living, he interrogates his fellow sailors in a series of semi-lucid exchanges. At mealtimes, or while gutting mounds of ling and redfish, he drifts into discussions of such diverse themes as manic depression and the death-wish, the idea that homo sapiens began life as a hermaphrodite, and the structural similarities between the many superstitions of trawlermen and those of the peoples of the Congo basin.
Providing a link for these themes should be impossible, were it not for the fact that the thread is O'Hanlon himself. This sort of narrative is only as stimulating as its creator: a writer with a wonderful imagination. As his sleep-deprivation worsens, he describes this state as a "chemical disruption" which "like real madness... can't be imagined".
But his rambling, repetitive, structure is the perfect vehicle for conveying what it, and the harrowing life of trawlermen, is like. It also belies the typical linearity of travel writing, showing it can express more than a rationalisation of experience.
As the hallucinatory tale nears its end, Robbie - one of O'Hanlon's best friends among the trawlermen - takes him aside. Jason, says Robbie, has only allowed him on board for one reason. Perhaps he will be able to write a book which will really help the trawlermen's wives and partners to understand what their lives at sea are like - to know them for who they are. O'Hanlon has repaid his ocean guides in spades.
Toby Green's 'Thomas More's Magician: a novel account of Utopia in Mexico' will be published by Weidenfeld in May