Evil eyes watched us from the river. By the light of my flashlight I could see at least two pairs, needlepoints of smoldering red emerging from the black depths of the Sepik. "Pukpuks!" whispered Pinga, our Papua New Guinean companion, shivering. I wondered if he was remembering the last time he'd slept on a mud bank like this one, when a pukpuk had come in the night and dragged him by the shirttail to within a foot of the water. Pukpuks: The word was infinitely more sinister than "crocodiles."

They had warned us not to camp near the Sepik, Papua New Guinea's longest and most crocodile-infested river, but tonight there had been no choice. Every other night on our canoe journey we had stayed in bush hauses, the abandoned hunting lodges of tribesmen who had retired to their permanent stilt-villages for the rainy season. But today we had paddled for hours through unbroken rain forest. Sago palms towered; limbum trees dipped their trailing roots into the stream, and dense pitpit reeds strangled the gray sand flats. By dusk there had been nothing for it but to moor the dugout by the tiny clearing we had sighted on the bank.

We piled our equipment near the trees and lit a giant fire to ward off snakes and crocodiles. "Pukpuk he no afraid fire," Pinga declared morosely. "He can eat anyt'ing -- bird, pig, fish, even shark. I see pukpuk one time fightin' shark. Pukpuk he win!" Uncheered by the story, the three of us huddled together near the warming flames, staring apprehensively into the darkness, straining for the sound of pukpuks. Suddenly there was a snapping report, as loud as a gunshot, from somewhere in the hidden inky mass of the river. It was followed by a curiously human grunt. Pinga's eyes glinted knowingly in the firelight. "Pukpuk, he get 'is dinna!" he said.

Crocodiles had been uppermost in our minds when my wife, Marinetta, and I had set off with Pinga from Green River, the farthest substation on the Upper Sepik, six days previously, with the intention of paddling down to Ambunti. We had spent more than 15 years between us in the arid lands of northern Africa, always traveling on foot or by traditional transport. Suddenly there had come the urge to seek a place that was always wet and always green, yet still beyond the reach of sealed roads and tourists in campers. After several days of trekking through unspoiled rain forest, we arrived at the long brown snake of the Sepik. It seemed to offer all the challenge we could want, and more.

"You won't see many crocs," said Martin, the kiap, or patrol officer, of Green River. "They sleep on the bottom and only hunt at night. They can't attack you in the water because they can't open their mouths." Pinga scoffed at this last bit of wisdom. As soon as we had pushed our canoe out into the swirling copper-colored stream, he commented, "You no believe that talk. Pukpuk he can open 'is mouth anywhere!"

Pinga knew. He was an expert. He'd come up to Green River hunting pukpuk for the skins. It was illegal, of course, but there were few other sources of cash for the Sepik people. They peddled the skins to licensed middlemen, who in turn peddled them to the big Japanese and Korean trading firms. Every year, thousands of Sepik crocs ended up as shoes and ladies' handbags in Tokyo and Seoul. Pinga described how the hunters would paddle out at night, finding the crocs with powerful flashlights.

"Some pukpuk, he no move when he see torch," he told us. The men would paddle up to the dazzled reptile and smash through its skull with their nine-foot-long harpoons of wood and steel. That, at least, was one way of doing it. But too many hunters now spied out nests and baited them with hook and meat, bagging both the mother and her unhatched offspring. Spear-hunting was dangerous, as the crocs sometimes lunged out of the water at the hunters. When you remembered the incredible instability of the dugout, you could see that this style of the chase was not for the fainthearted.

It was to avoid that instability that we had bought two dugouts, converting them into a catamaran with strands of split rattan. The double-hulled craft was stable but heavy and hard to handle in the dangerous Sepik crosscurrents. Often, on our six-day journey, we had to pull desperately against them to keep the canoe in midstream, dipping in our paddles again and again until our muscles screamed with exertion. Day in and day out we had paddled through the great chasms of the rain forest, an echo chamber oozing with sound. Beyond the pitpit reeds, trees foamed up like a tidal wave, draped with green creepers and interlaced with giant tree ferns. Enormous butterflies -- blue, black, yellow and orange -- played around the brilliant saffron cups of blooming mango trees, darting away as pieces of the bank broke off and pivoted whole sections of the forest into the river with a deafening roar.

Occasionally we passed villages -- stilted long houses balanced like flamingos over the mud flats. But we rarely went ashore, for Pinga was afraid of running into someone with a blood feud against his family. The Sepik people had long memories, and he wasn't eager to wake up with a spear in his neck as a result of some dispute involving a distant relative long ago.

Our impression of hostility seemed confirmed once when we paddled past a large settlement and shouted a hearty " 'Mornin'!" to some children playing on the bank. "You are all bastards!" came their unflinching reply. Pinga, a Seventh Day Adventist with a Bible in his sack, was incensed. "Satan, he speakin' through the mouths of children!" he exclaimed.

At midday we would stop paddling and let the dugout drift, while Pinga went through the essential ritual of "boiling banana." He would light his small brass cooker in the bow, scooping Sepik water into a pan and scalding a pound of small brown bananas in their skins. They were savory and tasted like potatoes. Usually, some time in the afternoon, we would sight a bush haus, a squat structure of limbum wood and sago-palm roofing, half buried in burgeoning vegetation. The locals cut vast, slippery tree trunks and toppled them across the mud flats as mooring jetties leading up to the house, which itself was entered by climbing a notched wooden pole. Here, six feet up, we were safe from snakes and marauding pukpuks, but not from the swarms of voracious Sepik mosquitoes, or natnats, that took possession of the buildings while the owners were away.

Entering one of these houses made me feel like Goldilocks. There were fishing traps, crocodile spears, bows and arrows, giant basins of folded limbum leaves and even the grass skirts worn by the women. In one house we found a chain of more than 30 pig jaws hanging from the roof -- a record of the number of wild boar the hunters had speared that season. Pinga would light a fire in one of the fish-smoking hearths to chase away the natnats and to cook saksak. More familiar as sago, this was the staple diet of the Sepik folk, scraped out of the trunk of the mature sago palm, kneaded, washed and finally boiled to produce a gelatin-like sausage of starch -- "Like rubba!" as Pinga described it.

Now we thought longingly of the bush hauses we had seen as we huddled around our moribund fire on the mud bank. About midnight, brilliant, blinding flashes of lightning suddenly split the darkness. "Naughty!" Pinga said, as if chiding the Almighty. Then he added a more placatory "No rain tonight, please!" Unmoved by his plea, the rain came down with ferocity a few moments later. The fire sparked and danced and began to fizzle. Quickly we lashed a waterproof sheet to the trees, crawling beneath it while the rain pounded and slashed across the mud. Pinga struggled to preserve a fragment of fire under the cover. Its smoke stung our eyes but failed to dislodge the resolute natnats that had followed us inside. Above us there was the grating creak of heavy boughs, reminding us disturbingly of the trees we had often seen plunging into the river during such storms. "Anyt'ing he can happen in the rain!" Pinga commented miserably.

I awoke from a watery dream in which Marinetta and I had been condemned to death on the bank of a river. We had appealed to our mild-mannered police custodians for a reprieve. "You'll have to wait and see!" we were told. At least, as the first feeble light began to rob the river of its menace, I realized we had survived the snakes, pukpuks, natnats and falling trees. Today we could hardly wait to get into the canoe and paddle away from the scene of last night's terror. But our luck was out. All morning a violent head wind pounded the dugout and threatened to turn us about. The effort of paddling was excruciating. To cap it all, one of the hulls suddenly sprang a leak and began shipping water.

"Canoe he no go long Ambunti," Pinga declared. There was nothing to do now but to halt at the nearest village and hire another canoe, possibly even a motorized dugout, to complete the journey to Ambunti, only a few hours away.

The next village was called Swagup, a muddy settlement of stilt houses on a baret -- a man-made channel connecting the village with the river's main course. As we landed, a group of aggressive-looking men gathered around us. It was an awkward moment both for us and for Pinga. These villagers belonged to the tribe of the insect cult people -- worshipers of the sago beetle, the dragonfly and the praying mantis -- the most ferocious fighters on the Upper Sepik.

"They don't follow the old religion anymore," Patrick, the local teacher, told me the next morning. He hailed from Maprik in the north and had been trained in a Jesuit mission. Inside the haus tambaran -- the village's "spirit house" -- however, his words were difficult to credit. Here, men sat around two massive crocodile-shaped drums, hewn out of solid tree trunks six generations before. The haus tambaran was traditionally the dwelling place of the tribal ancestors and, in headhunting days, was built with a human skull under each post. This smoky den must have housed some truly malevolent spirits. The insect people had murdered every man, woman and child in their neighboring villages several generations ago, leaving Swagup the only settlement on an otherwise uninhabited stretch of the Sepik. These very drums were the ones that had whipped the warriors into battle frenzy, accompanying their bloody sacrifices to the insect idols and driving them out to their war canoes in a bloody fever pitch. In this hypnotic state the warriors believed that anyone looking on their war canoes would see only the sacred insects that protected them, so the surprise of their attack would be complete.

A powerful, gloomy man called Andrew agreed to take us to Ambunti in his motorized dugout. He was a crocodile hunter who had just speared a 20-foot giant and was anxious to sell the skin in the village of Yessan on the way. The entire village turned out to watch him fix the tiny Yamaha motor on his canoe.

He hunched massive, pukpuk-spearing shoulders, and wrenched the starter. The engine didn't even turn over. He pulled again. Not even a splutter was to be heard. Again and again he pulled as frustration and rage grew increasingly evident on his face. Finally a relative took his place. Still nothing.

One by one, every man in the village tried to start that motor, all to no avail. After an hour of straining, Andrew was muttering ominously about "bad tambaran," and several of his family members were casting dark glances in our direction, as if we were somehow to blame.

It was shy, retiring Pinga who came out with the solution. "Change 'im spark plugs!" he said. The villagers turned their hostile glares upon him, but new spark plugs were brought and put in. At Andrew's first pull, the Yamaha exploded into life.

The motor canoes I had seen passing us on the river had looked wonderfully sleek, but once inside I found this one as unstable as a cork. We were forced to grip the sides to keep our balance. Including Patrick, who had decided to come along as interpreter, there were five passengers and a mountain of luggage.

Our first problem was negotiating the narrow baret, which had been blocked with trees and deadfall after the recent rain. Often Andrew had to cut the motor and lift it over submerged trunks, or all of us had to duck beneath trees that had fallen right across the baret and spanned it like bridges.

Once back on the main course, the motor cut out without warning. Each time Andrew got it started, it purred once in complaint, then cut out again. At last we were obliged to paddle to the next village, Yessan, where Andrew was to sell his crocodile skin. "Motor he got badpela tambaran," Andrew declared as he lept ashore. "He no go long Ambunti!" We eyed each other in dismay, but in his absence the unassuming Pinga examined the engine. "Motor, he all right," he reported, "Andrew, he no savvy drive 'im, tha's all."

The sun was going down by the time Andrew returned, still with his croc skin neatly folded under his arm. The dealer had offered him only 120 kinas for it, though whether it was this or Pinga's unexpected grasp of the motor that made him glower at us all, I never discovered. I suspected that he had been deliberately inept with his driving to keep us in Yessan for the night. I was right, and I quickly found out why.

No sooner had we paddled into the current than he began whispering to Patrick in pidgin. Patrick listened, then said, "Andrew doesn't want to go through the place where the river boils at night. He says it's guarded by the bad tambaran of a pukpuk." The place, he explained, was a dangerous whirlpool near the village of Yambon. The locals called it the Yambon Gate. I remembered my dream of being condemned to death near a river, and my blood ran cold.

We were committed. No one wanted to go back now that we were on our way. It was pitch dark and we were still paddling. Andrew wouldn't start the motor without a light, and I was the only one with a flashlight, which was at the bottom of my rucksack. The canoe wobbled frighteningly as I emptied it, item by item.

At last, I had the flashlight in hand. I switched it on. Nothing happened. Andrew swore venomous oaths as I fumbled with a spare bulb. A magical cone of light suddenly flashed into the night.

The engine started, and for a while we hummed along through the silent, eerie darkness. Then Patrick leaned over and whispered, "This is the place where the river boils!" At once the engine stopped. I heard the water sucking and tearing at the fragile hull; then Pinga's yell split the silence. "Paddle!" he cried. "Paddle or 'im go down!"

Far away, miles it seemed, the lamplight of Yambon village flickered like a weak candle. Then there was water in the canoe. "It's coming in!" Marinetta screeched. Pinga began to mop at the bilge with an old pullover, but the dark water poured in faster. "Oh my God!" Patrick screamed, "we're sinking!"

The water was up to our waists. I whipped off my bush hat in a futile attempt to help the bailing. We were all shouting unashamedly now, and Patrick was screaming, "Oy, me pellah-man, help!" and holding his basket of things over his head, ready to meet the river.

Any minute now, I thought. Marinetta and I were strong swimmers, but the river was wide and dark and probably full of pukpuks. Pinga was actually wrestling with Andrew to get hold of the motor. Miraculously, it started.

The craft sped through the water for a few seconds and the bilge emptied. Then the motor cut again and the canoe filled up worse than before. But those seconds had given us our chance. The lights were nearer, and there were answering shouts from the hidden shore.

Suddenly, the blinding glare of a hunting torch heaved back the night, and two slim canoes shot out of the darkness and drew alongside. I grabbed for one of them instinctively. Patrick was the first in, followed by Marinetta and me. As we moved slowly toward the welcoming oil lamps on the bank, Patrick turned to me, and I saw that he was still shaking. "Thank the Big Man," he said, "I'm from Maprik. I can't swim!"

In Ambunti the following day, the local headmaster told us, "None of you would have survived the Yambon Gate. It's too strong to swim there. More than 20 people have drowned there in the last few years. You would have been dragged down at once and the pukpuks would have taken you. There are some plenty big pukpuks 'round here." Then he showed us the gigantic skull of a crocodile caught near Yambon. Judging from the size of the cranium, it must have been 30 feet long. A State Department travel advisory on travel to Papua New Guinea is in effect, due to civil disturbances and violent crime throughout the country, and to terrorist activities near the Indonesian border; for details, contact the State Department's Citizens Emergency Center, 202-647-5225. For more information about travel to the country, contact the Embassy of Papua New Guinea, 1615 New Hampshire Ave. NW, Washington, D.C. 20009, 202-745-3680.

Michael Asher is the author of "Two Against the Sahara" (William Morrow).