The first day of India's vast Kumbh Mela festival has ended, with officials estimating that eight million people took to the waters at the confluence of the Ganges and Yamuna rivers.
The bathing was held under tight security with more than 30,000 police deployed at the grounds in Allahabad.
Hindus believe a festival dip at Sangam - where the rivers meet - will cleanse sins and help bring salvation.
The event, every 12 years, is billed as the biggest gathering on Earth.
The Kumbh Mela has its origins in Hindu mythology - many believe that when gods and demons fought over a pitcher of nectar, a few drops fell in the cities of Allahabad, Nasik, Ujjain and Haridwar - the four places where the Kumbh festival has been held for centuries.
As the sun set over Allahabad, a few hundred people were still bathing at Sangam and the crowd on the riverfront was thinning rapidly.
Some of the late evening bathers floated small paper or leaf boats with tiny earthen lamps set amidst marigold flowers into the river.
Official teams have been managing crowds on the river bank all day and, as soon as pilgrims finished bathing, they were encouraged to move away and make space for other bathers.
As dusk set in, police appeared to be satisfied with events.
"The day went off without any incident. The bathing went off peacefully," senior superintendent of police RKS Rathore told the BBC.
Police checkpoints lined roads leading to Allahabad.
The day began with groups of Naga sadhus or Hindu ascetics, many completely naked with ash-smeared bodies, sprinting into the chilly waters for a dip at the crack of dawn.
Some brandished swords and tridents, some stopped to smear their bodies and faces with coarse white sand from the river bed, while some chanted slogans and danced.
The ascetics are the biggest crowd pullers, but away from all the media attention were millions of ordinary Hindus, mostly rural folk, who queued patiently for hours to bathe in the holy waters.
"It is special to have a bath at this spot. Taking a bath here is like bathing in nectar itself," said Brijpal Kushwaha, who bathed at Sangam in the morning and again in the evening.
The pilgrims came from all corners of India, travelling by train, bus, rickshaw and covering the last miles on foot as the entire festival ground was turned into a pedestrian zone.
Many had slept out in the open for the past few nights, braving last week's sub-zero temperatures.
Shankari Devi from the Indian city of Udaipur arrived on Sunday and spent the night in the open but her conclusion this morning was that "we had a good bath so all the troubles were worth it".
Pilgrims appeared to make no demands on the authorities, and after performing their rituals, most appeared content.
"It's an auspicious day to bathe at Sangam. We come here to wash off our sins, and we have faith in the holy river," said Kismato Devi who had come for a bath from Tata town in the state of Jharkhand.
More than 100 million people are expected to attend the 55-day festival.
Tens of thousands of men, women and children have set up camp on the white sands of the river front.
Nevertheless, the festival is an immense logistical challenge and Allahabad has been preparing for months.
To cater for the millions of pilgrims expected there are 14 temporary hospitals, 243 doctors deployed round-the-clock and more than 40,000 toilets have been built for the pilgrims.
In 2001, more than 40 million people gathered on the main bathing day of the festival, breaking a record for the biggest human gathering.
The festival has prompted health concerns, however, with campaigners warning that the river waters are heavily polluted.
Most pilgrims drink a few drops of the Ganges water and many fill bottles to take home with them.
Authorities say they have taken steps to address the concerns.