Each year, a large number of devotees gather at Sagar island on Makar Sankranti. They take a dip where the Hoogly river meets the Bay of Bengal to mark the Gangasagar Mela.
The pilgrimage is the second largest congregation of people after the triennial ritual bathing of Kumbha Mela.
In 2020, organisers used QR code wrist bands to track pilgrims and help them find their families in case they get lost in the crowd. The island of Gangasagar is among the most popular Hindu pilgrimage places in India.