Loi Krathong festival is an ancient Thai tradition, which is takes place on the evening of the full moon of the 12th month (usually November). It is a very beautiful scene, with the full moon shining down on the river, perfect for floating Krathong. Loi (ลอย) means 'to float', and Krathong (กระทง) is the item which is floated down the river (see further).
In the past, lanterns were floated as part of Brahmanism, to worship the Gods; Siva, Vishnu, and Brahma. When Thai people adopted Buddhism, they adapted this ceremony in reverence to the goddess of the Mae Khong river (Mekong).
Floating Krathong along the river was allegedly created by Nang Noppamas; the favourite concubine of a Sukhothai King (Loethai). She made Krathong lotus-shaped, and gave it to the king of Sukhothai to float along the river. According to Sri Chula Lucks treatise, Phra Ruang (a Sukhothai King) said, 'From now on, on the full moon night of the twelfth lunar month, kings of Siam have to make a lotus-shaped floating lantern, to worship for ever after'.
In Rattanakosin period, people often made big and beautiful Krathong. According to Chao Phraya Dhipharachawong's historical annals:
In the twelfth lunar month on 14 and 15 waxing moon, I ask for members of the royal family and civil servants to make big-sized Krathongs, look like banana trunk rafts, sized 8-9 sauk in width (an ancient Thai measure of length) and 10-11 sauk tall. Competitions developed: For example, some imitate Krathong shaped as Mount Meru, while others made Krathong as baskets decorated with flowers. There are a lot of people to do these so they use a lot of money- about 20 chung (an ancient measure of weight).
Nowadays, Loi Krathong festival is held mostly in the Thai provinces. Particularly Chiang Mai, and Chiang Rai - there are Krathong parades, contests for making the best Krathong, and Noppamas beauty pageants.
The villagers in northern and north-eastern parts of Thailand also often send lanterns rising into the sky, made of coloured paper, to float across the heavens at night. The light from lanterns, with moonshine and stars glittering, can be seen for miles, and is very beautiful.