Kartik Purnima closes the month many consider the holiest of the lunar year. Pilgrims bathe in rivers and tanks before dawn, float small lamps on the water in the evening, and light rows of lamps at temples and on riverbanks in the rite called Dev Diwali, "the Diwali of the gods." It is held to be the day Shiva destroyed the demon Tripurasura, which gives it the additional name Tripurari Purnima, and it is also observed as the birth anniversary of Guru Nanak in the Sikh tradition and of Matsya, the fish avatar of Vishnu.
The festival falls on the full-moon day (Purnima) of Kartika, fifteen days after Diwali. The bathing and lamp rites are aligned to sunrise and sunset.
Its best-known expressions are the lamp-lit ghats of Varanasi for Dev Diwali, the Kartik Purnima fair at Pushkar in Rajasthan, and the Bali Jatra in Odisha, which recalls the region's old maritime trade.