The water was swirling and brown; it had the appearance of confectionery — a semi-translucent toffee or a dark fudge. A black dragonfly buzzed us like a tiny helicopter, tracking the boat for five seconds or so before darting away. On the riverbank — a solid wall of trees edged by a steep, smooth sandbank that was almost a beach — nothing stirred.

The Mekong is Southeast Asia’s greatest river, the world’s 10th longest, stretching nearly 3,000 miles from its source on the Tibetan Plateau to the South China Sea. It winds its way almost the full length of Laos, but my journey downriver covered just a short stretch, from the sultry border post of Huai Say to Luang Prabang. The trip was 186 miles. It took two days, though it felt much longer. Travelling by boat can be like that, but from the moment I arrived in Laos, it seemed that time somehow decelerated.

I’d half expected as much. During the period of French rule in the early 1900s, Laos became known as the land of the lotus-eaters. Resident fonctionnaires were notorious for their relaxed approach to matters colonial. Their successors at immigration also hailed from a more sedate, less frenetic era. They had a John Bull printing set that was shared between them — employing no less than eight separate stamps to create my visa, and another three to register my entry.

The result was a small work of art, which they took their time in creating. When I entered the immigration office, from the jetty where I’d arrived across the Mekong from Thailand, a man perched on the saddle of his bicycle lit a cigarette. He was still smoking half an hour later when I emerged. The visa cost me US$31, a dollar more than usual because I had arrived on a Saturday. A small notice taped to the front of their wooden counter explained the extra buck was added at weekends to pay for staff overtime.

For almost half its length, the Mekong rushes down from Tibet through a series of deep gorges before relaxing into the hills of northern Laos. The first two hours of my trip cut through two countries, Laos to the left, Thailand to the right, the river marking the border. Roads followed the banks on both sides, with telegraph poles marking the way to villages of concrete houses and tiled roofs. An assortment of rivercraft was moored at the foot of the high mud banks: simple dugouts and sleeker vessels with outboard motors, but none was as large as the old river barge, converted to take passengers, which I travelled in.

A woman carried two plastic buckets up from the river, slung on each end of a pole balanced across her shoulders. A man wearing a yellow baseball cap was digging with a hoe among neat rows of cabbages and beans trained up bamboo canes. Here and there the slithering banks had slumped, hefty slabs of elephant grass resting mid-slope below tree roots grasping the air before their eventual, inevitable tumble.

GRADUALLY THE uplands closed in, thinning the villages, displacing their lines of cabbages and beans, until we rounded a hillock and the captain told me we’d left Thailand behind.

The roads disappeared and forest took over, a twisted accumulation of plant life that crawled over the hilltops and crowded down to the waterline. The plastic buckets had gone and the concrete dwellings had vanished, replaced by sporadic villages still set in the age of bamboo. I wasn’t to see a wheeled vehicle again for two days. It was like entering a secret world.

Laos has been characterised by secrecy in recent times. The country was a clandestine battlefield during the Vietnam war, a spillover conflict that few outsiders knew anything about. The CIA set up a cloak-and-dagger airforce, and per person, Laos became the most heavily bombed nation in the history of warfare. All on the hush-hush.

The victorious communists weren’t keen on western visitors. But over the past decade, the country has slowly opened. My goal, Luang Prabang, the former royal capital and heart of Buddhism, is the jewel in the Laotian crown. Life on the river passed in slow motion, an effect heightened by the captain cutting his engines each time we approached a smaller boat, saving it from engulfment in our wash.

I watched two boys fishing from a dugout canoe, one with a paddle at the stern, his accomplice further forward wielding a net suspended between two bamboo poles. These were crossed and manipulated like a pair of giant scissors to open and close the mesh. The boys hadn’t caught anything before we passed.

()

The walls of mud had given way to sandy coves in-between jagged rocks and areas where vegetation sagged into the water. I learnt to tell when we were approaching a village because the banks were planted with rows of small, dark green peanut plants. Around one or two larger villages, whole hillsides had been cleared of their dense forest to cultivate sticky rice in near-vertical fields. The trees had been left standing along the ridges, resembling a line of mohican bristles on a shaven head.

Times recommends

• 'New York has lost its edge'
• The UK and Ireland's 25 best Christmas events
• Chalet Chef 2010: the winners