Naked Hindu ascetics and pilgrims are taking holy dips in sacred rivers in the first major bathing day of the Maha Kumbh festival, which is the largest religious congregation on Earth.

Millions of Hindu devotees, mystics and holy men and women from all across India flocked to the northern city of Prayagraj on Monday to kickstart the Maha Kumbh festival, which is being touted as the world's largest religious gathering.