It’s late evening in the city of Prayagraj and the roadside vendors selling snacks are packing up their wares to shut for the night.

India's Maha Kumbh Mela, or Great Pitcher Festival, is set to be the world's largest gathering of humanity, with 400 million visitors expected at the six-week event that began this week in the northern city of Prayagraj.

India's Mahakumbh Mela, which is the world's largest religious gathering, entered its second day. Over the next six weeks, 400 million visitors are expected to attend the festival. Thousands of religious leaders and pilgrims could be seen charging into the icy waters in a ritual they believe will cleanse them of sin and help them achieve salvation.

Millions of Hindu pilgrims gathered on Tuesday at the confluence of the Ganges, Yamuna and Sarasvati rivers to take part in the first holy bath of the Kumbh Mela, the world's largest religious gathering.

Nearly 15 million Hindus, six times the number expected, took a dip in freezing waters seeking absolution of their sins on Monday, the first day of India's festival that could draw the world's largest single gathering of humanity.