Kartik Poornima and Dev Diwali (Diwali of the Gods when Shiva defeated the Asura Trio, Tripurasura, sons of Tarakasura).
Huge gatherings on river banks or other water bodies all over India.
Seems bathing in winter gives special merit. A test of devotion.
Interesting story of how the three brothers were made sinners, otherwise Shiva and Vishnu were not acting against them.
The religious teachers after their task of corrupting the three Asuras was over, were asked to take birth in the Middle-East.
en.wikipedia.org
Shiva crushing Tripurasura (Click to enlarge the image).
