The boat races in Luang Prabang are to celebrate the religious spirit that is thought to reside at the junction of the Mekong and Nam Khan rivers. Each of the 25 boating teams leave an offering of food, flowers or money at the junction before the races begin. I don't know what they get if they win but they are very earnest in their pursuit of the finish line. The offering may be to escape drowning when your boat sinks. The event is celebrated by what looks like the entire country of Laos, it was so crowded, but it is only a local event. It does draw crowds from Thailand, since the event is celebrated for a week with triple the amount of street stalls. The Thais, being a very resourceful lot, can't resist getting in on anything where they can sell their wares.