TO TIMBUKTU: A Journey Down the Niger.<i> By Mark Jenkins</i> .<i> William Morrow: 240 pp., $25</i>

Early in his arduous, often fascinating, sometimes surreal descent by kayak down the Niger River, Mark Jenkins and his traveling companions--”four white guys from Wyoming paddling through black Africa”--find themselves gliding headlong into a “gigantic wall of debris.” They are gouged, slammed and nearly decapitated as a rushing current drags them through a maze of mangled trees. Jenkins’ description of this experience neatly captures the spirit of his adventure and the tone of his record of the trip, “To Timbuktu: A Journey Down the Niger.”

“I am in a flooding prison,” he writes. “Limbs are snatching at me from above and vines have wrapped around my hull and the current is pulling me sideways tipping me over. . . . Without thinking I begin hauling myself forward through the maze, my bow cleaving curtains of interlaced leaves, the keel rocking, the hull scraping, black water catching me and throwing me and it’s hell and I love it and the web is spreading and my boat shudders and I give one final heave-ho and I’m out, gliding over open water in dazzling sunshine.

“Yeesss!”

Here is a lust for rigorous adventure--”it’s hell and I love it”--not for the faint of heart or stomach. Traveling mostly by boat but also by motorcycle, buses and taxis as packed as sardine cans, Jenkins and his cohorts are attacked by a swarm of bees and charged by hippos; they pack 9-millimeter Rugers to ward off crocodiles (“To his right is a rippling wedge moving directly for him. Bulbous nose and slick eyes and then nothing for 15 feet until the ridge of a notched, swaying tail”); they heedlessly camp and swim in the midst of maggot flies, puff adders, black mambas, green mambas; they witness--and risk--the ravages of river blindness, bilharzia, typhus, sleeping sickness, guinea worm and malaria.

They also mix it up with all manner of self-appointed African guides, children awe-struck at the rare sight of white men, miracle-working mechanics, traditional chiefs, smugglers, corrupt police, prostitutes and knaves. They sit on the floors of conical mud huts raising toasts over tea and eating with their fingers. Reaching Timbuktu, Jenkins is served a ceremonial last supper consisting of millet and the head of a goat. Mohammad, his host, explains that “the brains and the eyes are a delicacy and that I am the guest of honor. I remove one of the eyeballs with my fingers and eat it. [He] plucks out the other, swallowing it whole. We eat the brains.”

A writer for Men’s Health, Backpacker, GQ and other magazines, Jenkins displays a Whitman-esque openness to experience. He has the descriptive and narrative skills to bring off a vivid and gritty portrait of a little-explored corner of the world.

“I am exactly where I want to be,” he writes. “One of the last obscure places. Somewhere not yet crosshatched with highways and bound with wire. Running the Niger is just a good excuse to come here.”

Jenkins’ journey begins in Conakry, the run-down coastal capital of the West African nation Guinea. It takes him roughly 750 miles along a meandering northward arc into the desert reaches of Mali. Jenkins is at his best conveying the mind-set of the Third World junkie who revels in a grittier, unvarnished, less antiseptic part of the world. Some of the most engaging sections of the narrative are flashbacks to an earlier trip with his buddy Mike Moe across North Africa, when the author was 18 and just getting his feet wet. He was robbed and nearly raped by border guards. He smoked hashish in Marrakech. He had an eerie liaison with a prostitute whose skin turned out to be covered with ugly burns and welts.

In fact, “To Timbuktu” is built around Jenkins’ brotherly bond with Moe, with whom he has shared a lifelong rapture for risks in difficult journeys such as this and their previous North African one. Their two other companions from Wyoming barely emerge as characters in the narrative, and eventually they break away. But Mark and Mike, who had left their pregnant wives at home in Wyoming, press ahead in their quest for rugged rewards. Recalling one of their many earlier bonding misadventures, Jenkins writes, “Every morning we walked into the ocean naked. We had been told there were sharks but we paid no attention. Before our brains were even awake, our bodies were surfing. The waves are enormous. Dangerous. They attacked us. Rammed us into the sand and knocked the wind out of us. Rolled us into shore trying to break off our arms and legs. Dragged us across the sand rasping our sunburned bodies. We loved it.”

Unfortunately, none of the Africans he meets emerges as a comparably complex, multidimensional character. The few with whom he spends significant time are sympathetic, to be sure, and there is some nicely handled dialogue that reveals some of the cultural gap that separates our Wyoming natives from their African interlocutors. There is their guide, who has 38 older brothers and imagines that white folks don’t love children because Jenkins plans to have only two. There is the chief who defends the widespread African practice of “female circumcision”--excision of the clitoris at puberty--on the ground that it offers women “freedom from desire.” But Jenkins is less adept at conveying how much these people have in common with us.

Part of the problem is Jenkins’ almost total lack of curiosity about the history or politics of the region. Interwoven throughout the narrative is a series of anecdotal flashbacks to the era of 19th century European explorers of the Niger region. These adventurers seem invariably to have come to ruin at the hands of warring tribes, rapacious chiefs or cannibals. One after another succumbs to malaria, typhoid or some other “bilious disorder.” These anecdotes are sometimes intriguing, but they give an American reader little sense of the roiling historical currents that have surged through the region before and since.

A reader unfamiliar with the great diversity of Africa might assume that what Jenkins is describing is typical; in fact, it is but one remote slice. Indeed, we are hardly aware of which country we’re passing through, apart from “Africa.”

Most of Jenkins’ journey takes place in Guinea, yet there is no reference to the centuries-long Atlantic slave trade, which had lasting repercussions throughout the region. There is scarcely a hint of roughly 70 years of French colonial rule and not a word about the notoriously brutal 26-year dictatorship of Ahmed Sekou Toure, the charismatic pan-Africanist-turned-despot who was toppled by a coup in 1984 that led to another decade of military rule. There is no mention of the years of Marxism and Cold War intrigue, nor of the civil war in neighboring Liberia, which has pushed more than 100,000 refugees into Guinea.

Even in this resolutely subjective narrative, the absence of context is problematical because it leaves the impression that our familiar American protagonists are passing through an alien, ahistorical vacuum, a land untouched by time, when in fact the harsh conditions Jenkins describes are very much the products of history and politics, locally and geopolitically. There is the danger of reinforcing Western preconceptions of Africa as a mysterious environment where people behave in inscrutable, atavistic ways.

Jenkins occasionally falls into this trap. At one point he compares his likable and highly capable Guinean guide, Sori, to a seeing-eye dog or a carrier pigeon: “He is primordial. His compass is inside.” More likely Sori is good at what he does, as are most people who are good at what they do, because he is intelligent and experienced and works at it.

To his credit, Jenkins populates his narrative with a wide variety of Africans, good and bad, and he clearly admires many of those he meets. He goes to some lengths to disabuse readers of some African stereotypes. At one moment, he highlights his own innate suspicion of unscrupulous porters, “loafers, drunkards, avaricious knaves” when in fact his porters turn out to be punctual, honest and awesomely hard-working.

Later, Jenkins encounters a drunken expatriate aid worker who subjects him to a diatribe about how lazy and corrupt Africans are. Jenkins leaves the expat behind and wanders into the crude brick hut of a blacksmith toiling late into the night with a small boy who jumps up and down on a bellows fashioned from a cow hide. “The blacksmith pulls out the spikes with his tongs and drops them on a makeshift anvil. Squatting in the dirt, hammer in one hand and tongs in the other, he pounds the two spikes together, smashing them into one. They chip and spark. After several hits he flips the lumps over and continues pounding until the metal has grown gray and inflexible. Then he lifts the lump with his tongs and puts it back in the coals and the little boy starts working the bellows again and the blacksmith wipes the sweat from his face.”

Explaining his itch to forsake more benign sojourns for dicier venues during this and his earlier African visit, Jenkins writes, “Europe wasn’t a mysterious land full of opportunities for valor and hardship.” On his first trip, he found what he was looking for in Morocco: “Tattooed women gorgeous as knives. Children innocent as ducklings flopping in the street with mangled wings. Upside-down sheep screaming then coughing then quiet. Muezzins wailing, blind men moaning. Radios cutting tin with a dull saw. Pyramids of oranges and dates and olives. Goat heads and sheep heads and shark heads. Entrails of everything. Catacombs of homes. Camels. Hooded men in djellabas drinking mint tea in the shadows. Thieves with daggers tailing us like jackals.

“We were exultant, insane with triumph.”

Flashing back to a trip across the desert by bus, Jenkins writes: “We never showered or shaved or saw a mirror. We thought of ourselves as wild and gallant and followed our noses straight into trouble we escaped only through pure luck. We assumed we would come out of every scrape unscathed. It is a naive and groundless faith but it is what you believe when you are 18, and because you believe, it often works.”

As on any journey, there are stretches of boredom, and in the retelling there are attempts at existential reverie and philosophizing that didn’t relieve the boredom for this reader. “Some of it was what you saw and where you went but most of it was what was going on inside you,” Jenkins writes. Not all of what goes on inside him will grab readers, but who needs it when what is going on around him builds up to moments like this:

“The women begin singing. They are clapping with their hands and singing with their heads thrown back, their necks thick, their warm tongues moving in their open mouths.

“Women come toward us, across the circle through the sound as if they are swimming through liquid. Each of us is taken by the hand into the circle and then Mike and John and Rick and Sori and I are dancing and all the women of the village are pouring in letting themselves go leaping and laughing and clapping their hands.

“The woman who chose me has slid one leg between my thighs and is undulating in waves. She is against me thrusting and rocking, moving me with her hips, her shoulders back her breasts pushed upward, her fingers twitching as if the shock of the drums were a current going through us. Another woman comes against my side and the two together enclose me between their hips and legs slowly turning until they face away and the orbs of their buttocks are holding me in the flood of their flesh.”

We can be grateful to Mark Jenkins for having both the nerve and the talent to bring us thigh to thigh with this all-too-neglected corner of the globe.