Loi Krathong is an annual festival in Thailand.
On the night of the 16th of November, Thai's all around the country make elaborate floats, usually made from banana leaves, decorated with flowers, candles and sparklers. The candles and sparklers are lit and then the whole decoration is floated down river. Some Thais will even attach some of their hair or finger nail, so as to float aware their troubles.
To see some photos of this years Loi Krathong festival please visit http://travel.sanook.com/bangkok/bangkok_08545.php?? Though this site is in Thai, the pictures more than make up for it.