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.

For pilgrims at the largest gathering of humanity, ritual bathing in India's holy rivers includes a key challenge -- finding your family and clothes after the chilly dip.

Vast crowds of Hindu pilgrims in India bathed in sacred waters as the Kumbh Mela festival opened on Monday, with organisers expecting 400 million people -- the world's largest gathering