Millions of Hindus are attending the Kumbh Mela festival in India - the biggest gathering of people in the world.
During the festival, which happens every 12 years and lasts for 55 days, people visit the city of Allahabad where two rivers, the Ganges and Yamuna, meet.
They bathe in the waters there which devotees believe will help them and protect them from harm.
With 100 million people expected to attend this year, it involves a lot of organisation.
This includes having doctors and temporary hospitals nearby and tents for people to stay in.
Hayley's been finding out more...