Riverboat skipper Chan Phoummy scanned the water ahead, and made constant minor adjustments to his course, twitching the wheel a fraction port or starboard. A slightly-built, middle-aged man, Chan has piloted boats along the Mekong in Laos for 25 years, yet he never takes the river for granted. ‘it’s always changing. No two journeys are the same," he said.

When we left Luang Prabang that morning, the Mekong had been broad, its coffee-coloured surface calm as a lake. Now it had narrowed and the water was becoming increasingly troubled, ruffled white by submerged rocks.

"You’d better walk this part. Every year there are accidents here," Chan warned and pulled the boat into the bank.

Scrambling along the rocky shore, my companions and I watched as the 22-metre wooden boat was skillfully brought pitching and rolling through the 500 metres of white water that swirled between a dog leg of rocks.

Only part of the Mekong’s 4,200-kilometre passage lies in Laos and yet it is this country which seems to belong most to the river. A sinuous thread running through the nation’s historical and cultural fabric, the Mekong has helped shape Lao’s past and holds a key to its future.

The Land of a Million Elephants, as Laos was originally known, grew up on the banks of the Mekong which flows through or borders the nation’s entire western flank. Luang Prabang, the old royal city founded in the 14th century overlooks the river. So, too, does the modern capital, Vientiane.

With 70 per cent of Lao territory taken up by mountain ranges, highlands and plateau, the Mekong is the economic life-line. Its flood plains provide the major wet-rice lands; its waters yield fish, the main source of protein; its passage of well over 1,500 kilometres affords the only communication link running north-south through the whole country.

As to the future, much of the Mekong’s enormous hydroelectric power potential lies in Laos as it is this mountainous region which provides most of the water in the river’s lower basin. Dams are, of course, controversial issues in today’s world, but if the huge hydroelectric generating capacity of the Mekong were tapped, Laos. currently one of the world’s poorest countries, could reap staggering revenues. Even now a hydroelectric dam on the Nam Ngum tributary near Vientiane has for several years been a major foreign-exchange earner through power exports to Thailand.

Yet like the country itself, for long shutting itself off from the outside world, the Mekong retains an air of mystery and romance. No dam slows its passage, and only now, since April 1994. has a bridge spanned its banks. Travelling the river remains, as I discovered, a journey of exploration, timeless in its enchantment.

It began, improbably enough amid Thai land’s burgeoning tourism industry at the so-called "Golden Triangle", where the Mekong and the tiny Ruak tributary momentarily bring together the borders of Thailand, Myanmar and Laos. Here the Thai banks bristle with an obtrusive tourism infrastructure — a jumble of restaurants, trashy stalls, guesthouses and deluxe hotels. Across the river Laos was different; quiet and empty with jungle vegetation.

There is no crossing point here, so we headed 80 kilometres downstream to Chiang Khong. The long-tailed boat we hired was to be our last taste of the modern world for the next four days. Freshly varnished and with funky green plastic cushions, it was kitsch but fun. The propeller, at the end of a long shaft, was driven by a I ,300 cc Toyota Car engine and the boatman, perched on a box next to this excess of power, proudly shouted above the din that he could get up to 100 kilometre per hour.

The Golden Triangle quickly vanished and the Mekong enveloped us. The river cut a course between high wooded hills, sometimes receding, more often hemming us in. Even in the dry season, before the Mekong becomes swollen by the monsoon rains, the current is swift. An old man had told me how the river can be "hungry" for a human soul. Local belief has it that if the Mekong does not claim a victim, the rains will not come and so the rice crop will fail.

We arrived safely. however, at the Thai settlement of Chiang Khong and took a ferry across to the Lao twin town of Ban Houei Sai. At this energetic little riverport, where black-dressed Hmong tribespeople mingle with the lowland Lao, we joined Chan Phoummy’s boat for a four-day run down to Vientiane via Luang Prabang, a journey of 757 kilometres. Our transport was a typical Lao wooden river boat, 22-metres long, two metres wide, with a wheel house at the bows, tiny toilet and cooking area at the stern and in between, beneath a flat roof, an empty hull.

Discomforts were, however, forgotten once we were underway. Although fairly narrow in these parts. the Mekong is exciting, flowing through wild, beautiful hill country.

After skirting the Thai border for a while, we headed east into Laos. The scenery became if anything even more spectacular and we met little on the river or its banks to detract from a feeling of isolation in a lost world. The sensation was not banished by the night’s stop at Pak Beng. This, the largest river settlement between Ban Houei Sai and Luang Prabang, is a collection of some 500 wooden houses nestling in the folds of the steep hills which trap the river in a narrow passage. It is an eerily isolated spot, given substance only by the river.

Throughout the next day the river maintained a stunning passage through a narrow valley. Forested mountains loomed on both sides, their slopes here and there ablaze as villagers burnt off the scrub to prepare the land for cultivation. Wisps of smoke curled over the surface of the water while ash-like flakes of black snow played in the air.

Traffic was few and far between and only occasionally did we pass other boats. Most were of the same design as ours, all were ladened with people, goods and even water buffalo. Now and then we spotted fishermen casting their nets from rocks, their solitude striking as villages were rarely seen.

By afternoon, we reached the mouth of the Nam Ou tributary where the Mekong curves to head south. The point is marked on the right bank by a sheer cliff into which is set Tham Ting, a 400-year-old cave temple. Stacked with hundreds of Buddha images, this is an especially sacred spot, once the venue for an annual celebration presided over by the King of Laos.

On the final stretch down to Luang Prabang, the river widens and there were more boats, more people. And gold, too. Camping out on the sandbanks were scores of families who for half the year are farmers but turn gold prospectors during the dry season, digging pay dirt out of shallow pits and washing it in wooden trays at the river’s edge. With luck there will be tiny flecks of gold glittering amid the blackish sand. One prospector claimed he found on average a gramme of gold a day.

After cave temples and gold seekers, Luang Prabang was a fitting terminus to an enchanted day. Shaded by trees and with an imposing site on the banks of the Mekong where it is joined by the Nam Khan river, this ancient royal city appeared to have changed little since travel writer Norman Lewis described it in 1950:

"Luang Prabang, on its tongue of land where the rivers meet, was a tiny Manhattan, but a Manhattan with holy men with yellow robes in its avenues, with pariah dogs, and garlanded pedicabs carrying somnolent Frenchmen nowhere, and doves in its sky. Down at the lower tip, where Wall Street should have been, was a great congestion of monasteries."

Life is, of course ,somewhat different now - the Frenchmen have been long gone and no king resides at the royal palace. Yet the mist-shrouded mountains have stood as mute sentinels and the city’s fabric endures as an outpost of old Asia.

Leaving Luang Prabang in the early morning, we were immediately plunged into a scene from Conrad. Mist rising like steam from the still water enveloped us, reducing visibility to but a few feet. Twice we had to stop. With the engines cut, the heavy silence conspired with the mist to wall us in. For half an hour, we waited until the weather cleared and slowly the river took form.

The most remarkable feature of the Mekong in this stretch is its vastly varying widths. From placid passages several hundred metres across, it will suddenly change mood and angrily tumble through rocky narrows. Yet it is an enchanting passage. Of the river here, explorer Henri Mouhot wrote in 1860: "In this part of the country... it everywhere runs between lofty mountains, down whose sides flow torrents, all bringing their tribute. There is almost an excess of grandeur. The eye rests constantly on these mountain slopes, clothed in the richest and thickest verdure."

For two days, with an overnight stop in the fairly prosperous river port of Pak Lay, our view was the same as Mauhot’s. Only after the river had swung east for its run to Vientiane were we brought back to the 20th century. The right bank once again became the Thai border, exposing the startling extent of later-day deforestation. Gone is Mouhot’s rich and thick verdure and Thailand’s hills are as bald as a bathing cap. In vivid contrast, the Lao side remains wooded, but for how long, I wondered.

Gradually, the hills recede and the valley broadens. Arriving at Vientiane at dusk was a disappointment. After Luang Prabang, the modern Lao capital seems an eccentric kind of place. a provincial town posing as a capital city. All but the main streets seem countrified with tree-lined grass verges, and a tranquil air is disturbed by little more than a passing bicycle.

There was little to keep me in the city and I was anxious to move on to see the final Lao stretch of the Mekong and one of its wonders, the Khone Falls. This is the largest waterfall on the entire river and the most formidable barrier to navigation.

The name Khone is used loosely and there are actually two principal cascades. Phacheng Falls and Somphamit Falls. These are but the two most dramatic features in a 13-kilometre stretch of rapids that form perhaps the single most wondrous passage of the Mekong.

Just before the river enters Cambodia it divides into several channels at the huge island of Khong. The distance between the westernmost and easternmost streams is 14 kilometres, the greatest width assumed by the river throughout its 4,200-kilometre course. Downstream of Khong numerous other smaller islands, of which Khone is one, create a maze of channels, some placid creeks, others raging torrents where the river plunges over rocks in a mad rush to get beyond these obstacles and continue a more leisurely journey.

With no time to travel the Mekong’s long middle reach in Laos, I flew from Vientiane to Pakse, gateway to Khone. This provincial capital, located on the left bank of the river at the junction of the Se Done tributary, is a major Mekong town, a crossroads for both road and river traffic.

Backed by a steep escarpment, the town is dominated by the former palace of Prince Boun Oum of Champasak, a delirious building of Oriental wedding cake architecture. Viewed close up, however, it was all too apparent that Pakse has seen better days. A handful of dilapidated colonial-period buildings lend an air of old-world charm, but the sights are quickly exhausted.

Far more delightful was Khinak. 136 kilometres downstream. The last riverine settlement of any note before the Cambodian border. Khinak is much smaller and much more charming than Pakse; the kind of place that makes you understand why the French colonials thought Laos an earthly paradise. At sunset children came to play in the river and sarong-clad women bathed with delicacy and grace.

Below Khinak the Mekong ceases to be its usual placid self. Disgruntled at having to find diverse paths between a hundred or so islands. both small and large, inhabited and uninhabited, it assumes an agitated mien along a series of channels, some extremely dangerous in parts. Attractive and deadly in these turbulent waters is the Phapheng Falls. 36 kilometres south of Khinak. Suddenly, without warning, a deceptively languid arm of the river crashes 15 metres over a rocky cascade into a maelstrom of white water.

A classic waterfall in appearance, Phapheng is intensely picturesque; Somphamit Falls, is not. Located upstream on a different branch of the river at the northern edge of Khone Island, it is set amid a mass of jagged rocks. Here the Mekong forces an angry passage in a series of cascades as opposed to Phapheng’s single drop. It was thrilling enough now at low water, but my guide described an awesome sight in the rainy season when it throws up sheets of spray to the accompaniment of a continuous thunderous roar.

At the same time as marvelling at a wonder of the Mekong, I couldn’t help being unnerved by this inhospitable face of the river. It was not difficult to share the utter despair the sight struck in the hearts of Doudart de Lagree and Francis Gamier, leaders of an expedition up the Mekong in the 1860s. It was at Khone that these French explorers saw their dream of a river road to China vanish, Never an easy river to navigate, the Mekong is impassable at Khone.