At the crack of dawn, Shiv Yogi Moni Swami rolls down a muddy track with his hands joined over his head as he prepares to take a dip in India's sacred Ganges river. Swami is just one of the estimated 10 million devout Hindus who have assembled for the 45-day Magh Mela -- a religious congregation held every year in January-February in the northern city of Allahabad.