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.

Hindu ascetics, from crowd of 35 million devotees attending, take dip in freezing waters, seeking absolution from sins.

Millions of Hindu devotees and mystics have gathered in the northern Indian city of Prayagraj for the Maha Kumbh festival, which is the largest religious congregation on earth.