Simon Chapman went into the jungle of northern Bolivia intending to tell the tale when he got out. When he briefly lost his fellow explorers and had to dump his canoe and washing kit, he kept his painting materials (an A5 spiral-bound cartridge pad and a pocket set of watercolours, "pound;6.99 at W H Smith") along with his medical supplies and mosquito net.
The Lancashire-based physics teacher has just published a travelogue about his quest for an elusive man-sized ape in one of the world's last wildernesses. He tells the tale in The Monster of the Madidi with an enthusiasm and honesty that at the same time persuades the reader there's nothing to it (just shoulder the backpack, fly to La Paz and sit on a bus downhill for 18 hours), and warns that only someone extremely well prepared and slightly deranged should try. Crocodiles, piranha, sweat bees (which land on you as soon as you sweat), and 24-hour ants (that's how long the bites hurt for) are the least of the obstacles.
But for a genuine whiff of adventure you have to peel back a layer of the tale and study the moss and fungus-stained pages of Simon's illustrated diary. Tiny flattened insects and blotches of watercolour ("the little pans of paint would clog up in the humidity; I'd try to dry them out by the campfire and the box would melt") are scattered beside lightning paintings ("my favourites are the five-minuters") of spider monkeys, river otters and tapir along with the occasional life-size tracing of a tree frog or lizard immobilised on the sketchbook page.
The pencilled captions, also written at high speed before exhaustion set in or he forgot the precise movements of the spider monkey, juxtapose high points ("Just saw an ocelot - I'm shaking so much with excitement I can hardly draw it") with low points ("I look terrible, my feet hurt and I'm pissed off"; "It's still cold and drizzly, a bit like Manchester in winter"), all with a powerful sense of immediacy.
Simon Chapman is addicted to rainforests. Whenever the demands of school and two small children pile up, he sits under a warm shower at home in Lancaster and slips into what he calls his "tree frog dream". In the same way, in the duller stretches of expeditions (too much time spent slogging through swamps and too little spotting ocelots) he finds himself thinking of school - "lessons that have gone wrong, things like that".
Early in his career, between his PGCE at Manchester University and his first job, he made trips of between one and six months to Indonesia, Guatemala and Latin America. Through his first long-term teaching job, at St Thomas Aquinas school in Manchester, he received an Earthwatch teacher's bursary in 1994 to study the group dynamics of macaque monkeys in Sri Lanka. "I thought they were rather like the lower end of my Year 10 at the time." All the trips are captured in his sketchbookdiaries, one of which won an award from BBC Wildlife magazine.
He inherited his passion for wildlife from his father, an engineer who taught him the art of still, silent observation on birdwatching trips in their village (Houghton on the hill, Leicestershire) and family holidays on the river near his grandparents' home in Essex. He also acquired a taste for night trekking at 13, when he and a friend would try to cross a row of village back gardens without being spotted. "It was the thing to do after youth club on hot summer nights."
Although his mother and grandparents were teachers (his mother, now retired, was deputy head of the village primary when he was growing up; his sister teaches maths in Southampton), he intended to follow his father's career path, and his degree at Manchester was in engineering. "But teaching had always been an option and suddenly it appealed a lot," he says. "After graduation I went into the education department on impulse and found they would take me for physics and technology."
He is second in the science department at SS John Fisher and Thomas More RC high school in Colne. The demands of the job and young family (Joseph, two, and Hannah, born last month) mean the flavour of his trips has changed. He and his wife, Carolyn, public art officer for Lancaster, once spent six months in Latin America together but last year they went to Crete. "It was too hot to do walks with Joseph in the backpack, but I did some paintings," says Simon.
But this summer he will return to the region that intrigues him most - the jungle on the slopes of the series of mountain ridges (serrianas) between the Andes and the Amazon basin. It's the territory where Arthur Conan Doyle is said to have set The Lost World; where the real Butch Cassidy and the Sundance Kid went when they needed to disappear; where Indiana Jones might go for a spot of training.
For The Monster of the Madidi, which Simon successfully pitched to agent Carolyn Whitaker in January 1999 after writing to everyone in The Writers' amp; Artists' Yearbook who handled travel books, he has fused accounts of three trips through the mountain jungles between 1995 and 1997, recorded separately in his diaries, into one. His goal was the upper reaches of the Madidi river, last charted by Colonel Percy Harrison Fawcett, who surveyed the borders of Bolivia's rubber country in 1906.
Colonel Fawcett, who set Simon on the trail with his reports for the Royal Geographic Society, was a friend of Conan Doyle (and possibly part of the inspiration for The Lost World, with his speculation that dinosaurs lived on in the Rio Verde region of Brazil). He disappeared in 1925 on another expedition, leaving reports of "some mysterious and enormous beastI possibly a primeval monster" and "an unusually large variety of the black howler (a type of monkey)".
Simon connected Colonel Fawcett's references with a TV documentary he had seen about Loys' Ape, a mysterious, tailless primate photographed by a Swiss geologist, Francis de Loys, in 1920, said to be 4ft 6ins tall, although de Loys forgot to stand next to the (dead) beast for scale and was later accused of faking the picture.
On his first trip to Bolivia in 1991, Simon heard tall jungle stories about the Mono Rey (king monkey): that it lived at the top of the serrianas and ripped up palm trees to eat the hearts; that it wasn't an ape, but a bear or a big spider monkey. He has still not seen one, although he did once meet a man whose father had met a man who had.
In the book, the quest for the Mono Rey remains the spur for the journeys, but gradually becomes less of a focus of the narrative as Simon's relationships with his travelling companions become increasingly volatile. He credits local guides, including the Janco brothers, with teaching him to pick up crocodiles, follow jungle trails and generally stay in one piece, but his fellow trekkers, Julian Singleton and Charlie Hruska, generate the most drama. Julian, a builder from London with a burning ambition to live with an indigenous jungle tribe, was almost a stranger when they set off on the first life-threatening voyage, and Simon had never met Charlie, an Australian sports angler.
"We're friends now, but at the time we were more like business partners. You can't do a trip like that alone - at least it's unwise - and it's unlikely that your friends will want to devote the time and money (his three Mono Rey trips cost a total of pound;4,200, plus pound;1,200 for a portable canoe) and do the training. Anyone who wants to do it is going to be very single-minded, but you have to find a way to act as a group."
Despite all that practice with the monkeys in Sri Lanka, Simon chose to downplay the group dynamics in the pencilled margins of his sketchbook, although he does hint in The Monster of the Madidi at the strain on relationships in a small party travelling under pressure. Julian's video diary, which was less discreet, sounds like Celebrity Big Brother material. Apart from the video habit - "I thought if that thing was shoved in my face once more I'd go crazy," says Simon - Julian irritated the others by being "annoyingly perfect most of the time".
Charlie, meanwhile, was dangerously absent-minded and prone to losing his fishing rod (an important source of food for the group). He realised his potential as the weakest link when he succumbed to foot fungus and dropped out of a renewed assault on the Madidi. Simon comes clean about his own contribution to the cocktail. "I was quite bossy, quite like a teacher I'm afraid. I think I was the leader - I tended to take charge, move us along. Oh dear, the others won't like that."
The book reveals that alongside the brutally bloke-ish pragmatism about each other's injuries (Simon's insect bites, Charlie's foot-rot, Julian's gut-rot), the team cared for each other's welfare and inevitably recovered from mishaps with tears and hugs. "Charlie getting lost was the worst, worst thing," Simon recalls. His trip this summer will generate more video diary material. "I'm going with two other teachers and we're all pretty opinionated."
Dave Clark, head of photographyvideo at Bolton Institute, and Derek Roddenberg, deputy head of geography at Central Lancaster high school, will join him to investigate Fawcett's claim that The Lost World was set in Brazil, with a TV film in mind. Mr Roddenberg also wants to compile some key stage 3 and 4 geography materials with an eco-thriller theme, and Simon is still keeping an eye out for the Mono Rey.
He is currently trying to train for the trip, although the foot and mouth crisis has put the Lancashire moors and the River Lune out of bounds, and he is working on a series of paperbacks for eight to 11-year-olds on the art of exploring, which Egmont Children's Books plans to publish next year. These are based on some of the questions his pupils have asked about his trips. "It's sometimes handy in class to be able to do a good monkey noise. But I'm not going to do it now."
The Monster of the Madidi: searching for the giant ape of the Bolivian jungle by Simon Chapman is published by Aurum Press (pound;16.99)