Curmudgeon in a Canoe : THE HAPPY ISLES OF OCEANIA: Paddling the Pacific, <i> By Paul Theroux (Putnam: $24.95; 528 pp.)</i>

Paul Theroux’s almost Napoleonic progress across the planet has taken him through Europe and Asia (“The Great Railway Bazaar”), China (“Riding the Iron Rooster”) and the Americas (“The Old Patagonian Express”). His latest travel dispatches are filed from an area which, almost uniquely for him, is entirely devoid of trains. The islands of Oceania must be negotiated by other means, and, this time, his chosen mode of transport is the canoe.

Actually, it’s a collapsible kayak, seagoing and German-built, and whenever he flies to a new island group, he paddles as far from the trappings of civilization as time and tide allow. He thus lands, and lives, on islands few outsiders ever get to see (a tent, sleeping bag and stove, together with plentiful supplies of noodles and green tea, accompany him everywhere). He visits villages, asks questions--in Pidgin, where necessary; Wonem dispela? What’s this?--and notes everything down: customs, language, legends, tribal lore, local flora and fauna, the lot.

But the journeys he made for this huge and exhilarating book were not made for the book alone. There is a personal dimension to the enterprise born of despair. On the first page we learn his marriage has failed and his doctor has warned he might have cancer. (It is a false alarm.) On the last, watching the total eclipse of the sun in Hawaii, he experiences a moment of happiness that is almost transcendental. So his traverse of the southern ocean was also therapeutic, a journey intended to soothe, heal, clarify--and renew.

Early on, he has “a clear recollection of the London I had left. . . . I saw people--writers--talking on television programs, and partygoers smoking, and snatching drinks from a waitress’s tray, and shrieking at each other. . . . ‘Bullshit!’ I yelled into the wind. . . . I felt I would never go back.”

Whatever it was he sought in Oceania, the Trobriands, or “Isles of Love,” seemed a good place to start. Fortuitously, his arrival coincides with the annual Yam Festival, a period of unbridled sexual license during which the women make all the running--” ’The girls and the women just rush at you,’ ” Theroux was told, “ ‘They grab you anywhere.’ ”

But it turns out to be a nasty business, pagan and brutish; gradually his beachcombing idyll begins to sour. Calling at a remote atoll to do some bird-watching, he is approached by a gang of vicious, spear-toting kids who threaten to kill him. Shaken, he becomes aware of ghosts, magic, superstitions, a looming undercurrent of violence. And finally he paddles away, acknowledging that the Arcadian vision he carries around in his head bears little relation to the haunted, menacing and unstable little societies he has found there.

And that, really, sets the agenda for what is to come. The Oceanians, their old innocence replaced by suspicion and introspection, are generally unwelcoming and--when he gets to Polynesia--idle and overweight to boot.

But here and there, traditional tasks are still being pursued. In the Solomons men dig in the sand for the giant eggs of megapode birds; hundreds are harvested daily to be sold or turned into enormous omelets. In Fiji a group of wild-eyed arsonists are single-mindedly burning down their island. On Tanna, in Vanuatu, members of the Cargo Cult sit around waiting for their American god, Jon Frum, to ship in unending supplies of dollars and consumer durables.

Jon Frum hasn’t got to Tanna because he is too busy handing out dollars and durables in American Samoa. And the folks there, entirely subsidized by generous handouts from Uncle Sam, demonstrate what will happen if Frum ever heads on down to Melanesia. American Samoa has become a garbage dump; junk even overflows into the lagoons, paving them with discarded drink cans (and dead coral). Their remarkable free-money economy, Theroux reports, has turned a race of warriors and master navigators into a tubby, profligate people shoving supermarket carts full of junk food.

In terms of obesity, though, few Samoans can challenge Tonga’s vast 308-pound monarch. When Theroux has his audience he notes that Taufa’ahua Tupou IV wears a black bombazine skirt and has a speech defect. Displaying a rather slushy way with consonants, His Majesty tells Theroux of his plans for a confederation of Polynesian states--many of which, of course, are on Theroux’s itinerary as he travels steadily east, through the Samoas, on to the Cook Islands, Tahiti, the lovely Marquesas, Easter Island and, finally, Hawaii.

Theroux’s style throughout is confrontational. What’s going on here? Who are you? Do you eat dogs? ( Yupela kaikai dok? ) Can I camp on your beach? Yet, though it records a journey that apparently brought him some measure of peace, it’s a curiously ill-tempered book.

People, places, whole nations incur his displeasure. He thinks the Tongans arrogant, uncivil, xenophobic, generally offensive. He hates Australians and New Zealanders. (The latters’ governor-general, Dame Cath Tizard, is judged at a dinner party to be “rather silly and shallow and unimaginative, as well as bossy, vain, and cunning, but principled in a smug and meddling way. A New Zealander to her fingertips. . . . “) He loathes the French--”among the most self-serving, manipulative, trivial-minded, obnoxious, cynical, and corrupting nations on the face of the earth.” And so on, right across the International Date Line, all the way to Honolulu.

Occasionally, camped on some isolated atoll, tucking into noodles and green tea, contentment is experienced and, here and there, engaging characters met; generally, though, he frets. Perhaps he needed more time. There is a welcoming, generous and beguiling side to life on many islands, though it won’t be felt by those in a hurry; finding “paradise” is just a happy combination of circumstances, patience and luck. I last glimpsed it, or something very similar, at a child’s birthday party on the hauntingly beautiful Marquesan island where Gauguin lies buried.

But Theroux is relentless in his quest. He doesn’t miss a trick. His energy and industry are awesome, his curiosity boundless. Noting a fisherman off a Vanuatu island, he paddles up, lashes their canoes together and questions him closely about his dialect--”What do you call this? What is that?”--noting down linguistic similarities with other groups. Everything goes into those notebooks, every shade and nuance of the trip. The result is perceptive, terribly readable and wickedly funny.

Since he traveled about the groups by air, there is little sense of their isolation from each other, the huge distances between. Yet that isolation makes them what they are. It also produces a need to close ranks against outsiders; territorial invasion remains part of their ancestral memory.

With its groups linked by chapter headings rather than connecting journeys, Theroux’s book has an anthologized feel, a collection of long magazine pieces. Yet, collectively, they powerfully evoke the region and add up to a brilliant and riveting read--hardly surprising, since they’re crafted by the finest practitioner of travel writing around today.