19th of January is the Epiphany day celebrated by Russian Orthodox Church. Usually, Russians celebrating it by plunging into the ice-cold water: resembling baptism of Christ in Jordan river. However, a sub-culture of amateur explorers “Diggers” (explorers of maze of tunnels underneath Moscow) have their own way to mark the holiday.
Traditionally, they gather next to the “Pillar of Death”, underground waterfall, underneath Niglinka river in Moscow. There they take part in the ceremony of showering under the freezing water. According to Diggers, this place is ‘mystical’ and ‘sacred’ to them.
– via ntv.livejournal.com: 1, 2