Laos: I'm drenched, you little squirts

I hear it before I feel it: a soft detonation, a bomb, and then the white powder flumps over my head. My eyes blink crazily. Through a white film, I see a boy raise a gun. I clutch the weapon at my side, lift it to my shoulder and take aim. Bang! Bang! The children collapse with laughter as water splatters their faces, dribbling lines through the pancake mix of flour and paint that cakes their cheeks. A few seconds later a flurry of flour bombs explodes above my head, the milky powder dusting my nose and eyelashes. A bucket is passed forward to the boy nearest to me on the cart and the women passing in front of me whoop and duck. I am drenched to the skin, gasping with laughter. Pii Mai in Luang Prabang is turning out to be much more fun than I had expected.

I hear it before I feel it: a soft detonation, a bomb, and then the white powder flumps over my head. My eyes blink crazily. Through a white film, I see a boy raise a gun. I clutch the weapon at my side, lift it to my shoulder and take aim. Bang! Bang! The children collapse with laughter as water splatters their faces, dribbling lines through the pancake mix of flour and paint that cakes their cheeks. A few seconds later a flurry of flour bombs explodes above my head, the milky powder dusting my nose and eyelashes. A bucket is passed forward to the boy nearest to me on the cart and the women passing in front of me whoop and duck. I am drenched to the skin, gasping with laughter. Pii Mai in Luang Prabang is turning out to be much more fun than I had expected.

Pii Mai is the foremost religious ceremony in the Lao calendar year. According to Chinese astrology, there are two days between the old and the new year when time stands still. In this temporal limbo the Lao people stop ageing and wash away their sins. You can witness New Year anywhere in Asia, but there can be no better place to see the festivities than in Luang Prabang. For in this town in northern Laos, the festival is celebrated much as it always has been. While the rest of Asia is modernising, buying up western goods and ideologies, Luang Prabang, isolated from the world by pot-holed roads and an impoverished government, has been left to itself. The result is a town that moves at its own pace: a pace that is dictated by the tides of the Nam Khan and Mekong and rivers it lies between, as well as the temples around which its heart beats.

At dawn, monks walk barefoot in the streets, begging bowls held aloft, ringing their bells for alms. In the evening, the crimson sun sets to the sound of temple gongs which resound across the forested valleys to the children playing below.

Pii Mai is the only time at which the town rouses itself from this tranquillity. Then people flood in from the surrounding mountains, among them Hmong and Mien. These tribespeople live in thatched huts and share the forests with rare beasts; Javanese two-horned rhinos, barking deer, clouded leopards. Lao is not so much a nation state as a mixture of different tribal groups, and the majority of the population still gets its protein from wild rather than farmed animals. At Pii Mai, Luang Prabang bulges at the seams to accommodate its visitors, many of whom sleep on the cool, stone floors of the temples. Foreigners are fortunate. In the poorest country in Asia, the tourist dollar goes a long way, and those with the means can choose between teak-terraced bungalows overlooking the Nam Khan, to stucco-fronted colonial villas on the Unesco-protected high street.

Like other visitors before me, I make assumptions about this festival. I expect serenity: incense wafting across the rivers, devout Buddhists muttering prayers. Instead, I find myself in an atmosphere of riotous carnival where tourists and locals alike are thrown into a heady, unstoppable waterfight.

This is no sport for softies. Children line the streets armed with water pistols: vast Uzis in pink and orange plastic with alternating barrels and extra-large ammo tanks. Behind them, their parents tug fresh buckets of water onto the street for refills. Others hire open-backed trucks to drive their children around town, so that they can slosh water onto passing motorcyclists. One man is knocked off his motorbike by the weight of water thrown at him. For children, Pii Mai is heaven: chucking buckets of water at unsuspecting adults is actively encouraged, symbolising, as it does, the spiritual spring clean that this festival is all about.

The celebrations have a time-worn chronology. On the first day, families stroll down to the shore of the Mekong, where narrow boats wait to take them to the other side of the river. Here they build stupas in the sand, garlanding them in flour and marigolds. Children carry birdcages to the water and release the trilling creatures to the sky. On the banks behind, young women sell green coconuts under awnings. They wear Lao traditional dress – a sarong woven in glittering threads, with a fresh white shirt, despite the children's flour and dye bombs. That night, the tide will wash away the stupas; this is a blessing, as each grain of sand is said to represent a separate sin.

The next day is the big event: the procession of the Pa Bang. This golden statue of the Buddha, given to the Lao King by the Khmer monarchy in the 15th century, is Luang Prabang's talisman and namesake. Every year, the Pa Bang is carried from the Royal Palace through the town, to be laid in a sacred monastery for a three-day cleansing ceremony. Icy water, sprayed down my back by a cheeky monk comes as a relief: April is the hottest time of year in Luang Prabang, with temperatures exceeding 40C. There are shouts, a trumpet, and the procession draws into sight.

The beauty queen, a maiden who has been chosen the night before from the local provinces, leads the way. Seated atop a giant painted elephant, she nods to the people below, her pretty dark hair coiled up in strings of golden beads. Behind her comes an army of younger girls, aspiring beauty queens all, who carry lollipop-coloured parasols and silver caskets studded with frangipani. Next come the monks, the most senior borne on orange litters. The procession weaves towards Wat Xieng Thong, a ravishing 16th-century monastery, where the monks alight to be anointed with water. This is the final blessing. The guardians of Luang Prabang have been cleansed again and the new year can begin.

Getting there

West East Travel (0870-220 1001; www.westeasttravel.com) offers return flights to Vientiane with Thai Air from £590. For onward travel to Luang Prabang, fly with Lao Aviation from around £50 through Diethelm Travel (00 856 71 215 920) or take the 10-hour bus journey, about £6, from Talaat Laeng bus station on Setthathirath Road. Thai Airways (020-7491 7953; www.thaiairways.com) offers return flights from London to Luang Prabang, via Bangkok and Vientiane, for £870.20.

Being there

Thongbay Guest House, Ban Vieng May, Vat Sakem (00 856-20 519 010) offers Lao bungalows for £20 b&b. Villa Santi, Thanon Xieng Thong (00 856 71 212 267) is a hotel in a French-Lao colonial villa with doubles from £75.