Thula Snanam, also referred as Tula Punya Snanam, is an important bathing ritual observed in Tamil Nadu. It is observed in the Tamil Month Aippasi (October – November), which is also referred as Thula – Aipassi. In the month, people wake up in the early morning and take holy
dip in the River Cauvery (Kaveri). Puranas like Agni Purana narrates about the importance of the holy bath. Thula Snanam begins on October 17 and ends on November 16 with Muduvan Muzhuku.

Interestingly, during the same period the Kartik Snan takes place in North India . Lord Krishna explained about the importance of this period of year to Satyabhama.
Scriptures indicate that bathing in River Kaveri during Tula-Aipassi month will help in absolving all the sins. Taking a holy dip in morning in Cauvery is equated to taking a dip in Ganga at Prayag and at other holy Tirthas.
Special pujas dedicated to Kaveri are also held during the month.