Buckets of holy water slung over their shoulders, millions of Hindu devotees have been walking for days.

The water, scooped up from the holy river Ganges, is destined for the pilgrims’ local temples. And the precious cargo must be treated delicately: spilling a single drop, or touching another person before reaching home, would cancel out the devotional deed.

Breaking up the wearying journey, devotees gather for outbreaks of extravagant revelry – ground-shaking music and dancing fueled by devotion, ganja and alcohol, as befits in their eyes Shiva, the Hindu god of destruction and renewal, to whom the festival is dedicated.

This is the Kanwar Yatra festival, which draws tens of millions onto northern India’s roads each year. It’s gotten louder and rowdier in recent years – and increasingly bound up with the Hindu-nationalist politics of Prime Minister Narendra Modi.

Inside a tent along the route, the air was thick with marijuana and music. Devotees sipped bhang, a preparation of cannabis with milk and other fruits, and broke into dance.