The end of the retreat period observed during three months by Buddhist monks is cerebrated during the full moon of lunar month of Assoch. This is commonly called Chenh Vossa (getting out of the Vossa rainy season).
Monks get together in all pagodas to confess their sins. The publics then bring their traditional offerings and give them to the monks on the Day of Pchum Ben (the day offerings are collected).
In addition to prayers and recitations of the Buddhist scripture, reading of Vessantara Jataka is also done. It is the story of one of the previous lives of the Lord Buddha, in which he by now detached from the material wealth of the world, donated his wife and children to the beggar.
On this occasion, the raft made of banana trunks and lit with oriflammes and candles is
transported to the riverside. The raft represents either a temple, or Preah Colamonei. This latter is topped by a king of lantern called Kansom Taor, which represents the hive of a species of a giant bee.
At the riverside, the raft is loaded with offerings after an invocation of the Triple Gems: "The Buddha, the Buddha Law, and the monk". Prayers are recited and homage is paid to the Buddha's Footprint. The villagers ask the Water and the Earth for forgiveness for having polluted them during the course of year. Following this, the raft is released into the river; richly decorated small boats carrying monks, followed by procession, tow it. In many villages, boat races are often held during this occasion.
Several legends explain the customs of the "Floating of the Lights", but two of them are particularly well known. It is said the festival is help to pay homage to a tooth of the Buddha kept by the king of Naga (mythological snake) at the bottom of the water.
Another legend says it is memory of the day when, at the demand of the Naga, Lord Buddha left his footprint so that the aquatic animals may participate in the cult. The same legend also explains the Water Festival that is held a week later.