The dark ribbon curls down a dirt embankment and flows into the Ganges River. "That's toxic runoff," says Rakesh Jaiswal, a 48-year-old environmental activist, as he leads me along the refuse ...

The naga sadhus—the iconic naked holy men of the Kumbh Mela—parade en masse to bathe in the waters of the Ganges River, followed by the millions of pilgrims who have also come to partake in ...