The Kumbh Mela festival, the largest religious gathering in the world, has begun in the northern Indian city of Prayagraj.

India began on Monday its Maha Kumbh Mela, or Great Pitcher Festival, which is expected to draw more than 400 million visitors to the northern city of Prayagraj over six weeks, making for the largest gathering of humanity in the world.

The Kumbh Mela has grown over the years and has transformed from a religious gathering to much more. It provides a perfect combination of spirituality, adventure, and cultural diversity that makes it a very attractive destination for the young crowd.

Vast crowds of Hindu pilgrims in India bathed in sacred waters as the Kumbh Mela festival opened on Monday, with organisers expecting 400 million people -- the world's largest gathering of humanity -- to assemble over six weeks.India is the world's most populous nation, with 1.4 billion people, and so is used to large crowds.

While the Kumbh Mela festival is ordinarly held every three years, rotating between several holy cities on the banks of these rivers, the Maha Kumbh Mela occurs only once every 12 years. Maha means “great”, and the event attracts the most devotees because it is considered the most auspicious and holy in the cycle.