Loy Krathong
Loy Krathong takes place on a different date in each year (21st November in 2010) as it is is based on the full moon night of the twelfth lunar month which is usually falls in November. It is widely regarded as the most most romantic of Thai festivals and if your in Thailand around November it would be best to be close to a body of water if you wish to experience this charming ritual.
"Loy' is the Thai word for float and "Krathong" means circular object decorated with banana leaves and flowers and these are exactly what you will see in their hundreds if not thousands floating down rivers, bobbing gently in lakes and floating out to sea all over Thailand on the night of the full moon. With each one illuminated by candles it is clear why the festival is viewed as romantic. 
Couples and singles alike launch their Krathong in the hope of gaining insight into their romantic future, immediately sinking to the murky depths is not viewed as a good sign!
The Krathong also symbolises the taking away of any previous bad luck experienced in the preceding year.
Couple the thousands of Krathong shimmering on the waters surface with the many Chinese lanterns that are launched high into the sky Loy Krathong can be a truly visually stunning sight.
If you wish to participate yourself there will be a multitude of Krathong on offer close to any area that it is taking place. They range from around 30 baht for a small, plain one to around 100 baht for the more elaborate.
Once again Nong Prajak Park is the centre of activities for Udon Thai.