This is the "Lai Heua Fai" Festival, the festival of the fire boat.
The day is celebrated by illuminated boat processions handmade with bamboo and banana trunks, colourfully decorated with candles and money. Each family has to make one, each people has to throw out one illuminated little boat on the Mekong, wishing good luck for the future and paying respect to the spirit of the waters. This is more than 20000 boats down slowly the river during the night...
In Luang Prabang, a big parade happens that day. Most of the village of the town (around 20) are building their own big boat, competing every year for the most beautiful one. Ethnic groups are wearing their traditional clothes, people singing, chanting, dancing, fireworks are launched all around...
This is certainly the most attractive and impressive festival in Luang Prabang all year.