Loy Krathong is held on the full moon of the 12th month in the traditional Thai lunar calendar. In the western calendar this usually falls in November.

"Loi" means "to float". "Krathong" is a raft about a handspan in diameter traditionally made from a section of banana tree trunk (although modern-day versions use specially made bread 'flowers' and may use styrofoam), decorated with elaborately-folded banana leaves, flowers, candles, incense sticks etc. During the night of the full moon, many people will release a small raft like this on a river. Governmental offices, corporations and other organizations also build much bigger and more elaborate rafts, and these are often judged in contests. In addition, fireworksand beauty contests take place during the festival.

- Wikipedia

So at our school we celebrated Loy Krathong by dressing up, making "Krathongs" or boats made of wax and banana leaves and having a parade and celebration in the school oval. It was a long day in the hot sun, but it was quite fun. As I understand it, thai people float their Kathongs on the river to float away their sins and begin fresh. Its also a celebration to thank the goddess of the water for the water itself. Its quite a party in the Buddist faith. As you can see, our kids at school looked adorable.