Take a deep dip in the Ganges

Uma and Wanda were uncertain. "Do you dip five times or is it three?" And they had been overloaded with requests. "Salwa was quite insisting that I wash away her sins for her, but she didn't say exactly what they were."

The boatman watched in disbelief as these two grandes dames of the Bombay social whirl had their butler arrange the blankets and the generous quantities of luggage that an afternoon of boating on the Ganges seemed to require.

We were setting out to visit the sangam, the holy confluence of three great rivers: the Ganges, the Yamuna and the Saraswati (the latter being a legendary waterway), and the ladies were determined to fulfil their religious duties in style.

Once away from the muddy bank, the boatman pulled hard at the oars, gently manoeuvring us around one of the huge white sandbanks exposed during the dry season. Every 12 years these become handy camp grounds for pilgrims at the Kumbh Mela gathering - 30 million of them were there last year. Now the only people to be seen were bent over, probing the muddy edges with sticks.

"They are searching for money," said the butler. "People throw it from the trains and buses as they cross the bridges of Allahabad upriver." Judging by the industrious activity, this was no idle source of supplementary income but an established profession. One man had even ingeniously devised a magnetic fishing net with which to trawl the shallows.

Our boat came now into the main stream of the Ganges, the brown waters sucking greedily at the yard-high face of the mudbank which crumbled away like a cheese. The body of a woman, face down, hair adrift like a skein of weed, nudged gently at a promontory. Those who die in childbirth or from snakebite, smallpox or burns are excused cremation and placed in the river, a boon for the crocodiles and fish.

The walls and towers of Allahabad Fort reddened in the late sunshine and looked gorgeously romantic - exactly in the manner associated with the Daniell brothers, who had painted them in the early 19th century. Built on the land between two rivers, Allahabad Fort is on the Yamuna's north bank as it curls in to meet the greater Ganges.

By some trick of topography and hydrology the waters are conspicuously different in colour. On one side is the clear Yamuna, on the other the brown silt of the Ganges, and they slide alongside each other for some distance, proudly refusing to mingle, a natural phenomenon that for thousands of years has made the sangam one of the holiest sites in India.

Along the line of confluence itself, a string of boats were staked out and the ladies began to get anxious: "So many people dipping! Kevin, will you dip?" It seemed odd but I had not considered it until then, certainly had brought no spare clothes or a towel. I had come to observe a phenomenon: the Hindus bathing on the eve of Shivaratri, the night of Shiva.

At this time, young men would gather water from the sangam and walk 75 miles along Emperor Akbar's 16th century Great Trunk Road to Benares where they would offer their precious cargo in the temple. It had not crossed my mind to join in, become part of the occasion.

Clouds of incense smoke wafted around us; other vessels were tying up and the people leaping off into the water, swept up by the spirit of the moment. An old lady was pouring water over her husband from a copper pot, her face full of tenderness.

A poojari, a string over one shoulder revealing his caste, stepped from the next boat into mine. "You are dipping?" he asked.

"I didn't bring a towel or spare clothes."

"It is not necessary," he said. "We have god's towel." He pointed up at the late sun, now sinking over Allahabad." I put my camera back in my bag: it was time to participate, not observe. Laughing, I stepped off the boat and into the water.

Kevin Rushby's fourth book, Children of Kali: Through India in Search of Bandits, the Thug Culture and the British Raj, is out on 29 August (Constable, £16.99).