OUR BOATMAN CUT his motor and the dugout drifted to a stop. Eric SinO naya, my guide, pointed to a branch 20 feet above.

At first I could see nothing but leaves. Then, gradually, the outlines of a 12-foot boa constrictor began to appear, its perfectly camouflaged coils balanced in a fork of the branch, motionless except for its darting tongue.

This was the first of many such sightings during a day in the Malaysian jungle.

Jungle is the dominant physical feature of Southeast Asia. From Vietnam to Java, 600 miles below the equator, from Sumatra on the west across the South China Sea to Borneo, the land is covered with dense rain forest and jungle.

In the center of this vast area lies West Malaysia, its 50,000 square miles occupying the lower half of the peninsula which hangs like a ripe jackfruit below the Asian mainland. A tropical nation, Malaysia is hot and humid, except in the highlands where mountain temperatures range from 55 degrees at night to the low 70s at noon.

If a traveler wants to experience what much of this region is like, it is essential to leave the well-known tourist areas and visit the jungles. They are shrinking each year under the chainsaws of the timber companies, so I felt I could not pass up the opportunity.

My first day in Kuantan, on the underdeveloped east coast, I looked up Eric Sinnaya, a young but knowledgeable guide who had shown me around before.

An Indian who grew up on the west coast, Eric runs his own tour agency out of the Merlin Hotel in Kuantan. Mastery of half a dozen languages has enabled him to become friendly with the local aborigine tribes as well as with American and European travelers. He takes pains to introduce his clients to the people, animals, birds and flowers of the region and builds in enough flexibility on his tours so that each person has time to investigate whatever takes his fancy along the way.

Eric invited me to go along on a trip he was escorting to Chini Lake. This is an inland body of water that can be reached only by small boat through the jungle on the Chini River.

Malaysia is home to many of the earth's more fearsome creatures and the jungle is where they live and work. Among the more exotic dwellers of this self-contained world are elephants, honey bears, Malayan tigers (who sometimes prey on planatation workers), monkeys, crocodiles, awesome reticulated pythons (which sometimes reach a length of 30 feet), and a variety of poisonous snakes, including the aggressive king cobra.

Not all wildlife here is dangerous. Scores of brightly colored birds and outsized butterflies defy the laws of camouflage, and decorate the jungle's drab browns and greens.

The next morning, two young German couples, Eric and I set off for the interior. It took only a short time to drive the 60 miles southwest of Kuantan to Belimbing Village on the shore of Malaysia's longest river, the Pahang. As we neared the village, a 10-foot cobra raced across the road in front of us.

Outside the air-conditioned taxis, we felt the full brunt of Malaysia's 90-degree heat and humidity, which descended on us like a warm blanket, as we hiked to the boat landing.

From here on we would be on the water in narrow, four-passenger, flat-bottomed dugouts powered by small outboard motors. Fully loaded, these fragile craft rode only a few inches above the water.

We set off across the muddy half-wide Pahang. The solid wall of trees on the opposite bank yielded an invisible opening at the last minute and we slid under a canopy of branches into another world.

The bright sunlight was gone and we were gliding up the Chini River, a narrow ribbon of black water never more than 25 feet from bank to bank. The surface mirrored the trees above. The suddenly cool air was musty and still; the odor of rotting leaves and wet earth filled our nostrils.

Many of the trees towered 200 feet into the unseen sky. Vines trailed from their branches, dipping into the water. It was like riding through a dark tunnel in an unreal world. Smooth tree trunks, three feet across, disappeared into the foliage above while, near the marshy ground, they broadened out and their long roots, glistening with dampness, crept across the jungle floor into the darkness and down the high slippery banks into the river.

At first, there was no undergrowth, and yet we could see only a few yards into the gloom beyond the banks. Although nothing moved, we felt watched.

The convoluted river twisted wildly and our boatman needed all his skill to negotiate its turns. Eventually, the marsh gave way to drier ground covered with heavy underbrush; shafts of sunlight filtered through the branches.

It was here we spotted the first boa in the branches and stopped the dugout. Several times in the next hour, we halted to observe these great snakes as they rested or hunted high above.

People lived in this jungle but we saw no sign of them during the first hour.

Finally, we suddenly heard laughter and just beyond another hairpin turn, on a log landing, appeared half a dozen small brown children, the boys naked, the girls wearing modest scraps of cloth. They were washing vegetables in the river. As we neared the landing, women and older children lined the bank above, watching us.

These were Malaysia's indigenous people. Members of the Jakun tribe, the diminutive aborigines have been a part of the jungle for centuries. Part-time slash-and-burn farmers, the Jakun grow a few root vegetables, fish in the river and hunt monkeys and wild pig with homemade spears, blow guns and poisoned darts.

The men were away working in the jungle but the women welcomed us, gravely accepting Eric's gift of bananas. Their small clearing was only large enough to hold a small vegetable plot and four impermanent-looking huts. A few scraps of clothing, some weapons and a handful of fire-blackened pots were their only their possessions.

While Eric talked with the women in Archaic Malay, we held their babies, took pictures and looked over the huts.

Back on the river, we soon noticed the trees thinning out. As the light grew stronger, the river narrowed to only a few feet. Pushing through dense reeds, we finally broke through into the open and there was Chini Lake.

Dotted with inlets and small islands of high reeds, the lake appeared to be about three miles long and was surrounded by low jungle-clad hills. At the lower end, the water was choked with acres of lotuses. Their round, rubbery leaves, two feet across, lay flat on the water and the foot-wide blossoms, pink petals framing bright yellow centers, rose on thick stalks a foot above the surface.

We stopped to take pictures while the women picked blossoms, and then we set off across the lake. A welcome breeze ruffled the water, throwing a cooling spray over the boats.

Twenty minutes later, we stepped ashore in an open clearing where we ate the lunch Eric had brought. Chini Village, home of another group of Jakun, lay just over the hill, and small boys hovered around us enjoying the watermelon we offered them. Women and girls watched from a discreet distance.

Later, we visited the village and Eric demonstrated the use of the long bamboo blow guns. An old woman told Eric that the men were off on a two-day hunt for monkey and wild pig. We started back in mid-afternoon. Riding with the river's current, the trip downstream was quiet and by 5:30 we were back in Kuantan.

Although we has seen no big reticulated pythons, there had been much to remember. To the Jakun, the giant snakes are a real threat. Although their normal diet consists of deer, goats and wild pig, they are known to dine on humans as well. Southeast Asian newspapers report regularly about these grizzly events, which take place throughout the region.

The next evening over dinner, Eric Sinnaya recounted the story, told to him by the Jakun, of how they cope with attacks by the big python.

Over many generations, the Jakun had observed that after wrapping itself tightly around a victim, the snake would squeeze until it heard bones snapping, at which point it would release its coils and swallow its prey.

When a python captured an unfortunate Jakun, his friends gathered up some bamboo sticks and bent them slowly. To the snake, the sound of the breaking bamboo was identical to that of snapping bones. Hearing this, the python would loosen its embrace and the aborigines would rush in and rescue their friend.

Conventional western wisdom has it that snakes cannot "hear." The Jakun believe otherwise.

Once home, I discovered a Science Magazine article (March 14, 1969) which supports the Jakun theory: Researchers Peter Hartline and Howard Campbell found that airborne sounds evoked responses in certain species of three snake families. Concerning the boa constrictor, they wrote, "If a brain response is accepted as indicative of hearing, these snakes can hear airborne sounds."

Not all visitors will be lucky enough to meet Malaysia's largest and most spectacular wild animals (except in zoos), but they will meet many of her people. A week or two spent in this emerging country can be a memorable experience, especially for those who venture outside the cities.