Russian Orthodox Christians in Moscow celebrate the feast of Epiphany, commemorating the baptism of Jesus Christ in the River Jordan.
A priest blesses the water in a hole cut in the frozen Moskva River.
The bravest devotees take a ritual dip in the freezing water, which they believe symbolically cleanses them of sin.
They also believe it is good for your health.
(SOUNDBITE) (Russian) MOSCOW RESIDENT YURI NIKOLAYEVICH, SAYING:
"I am a winter swimmer, there's a place near here where I have been winter swimming for seven years already. On such a great holiday like Epiphany, which is one of the twelve great feasts, the feeling is amazing, you don't feel the cold and you feel God's grace."
But the holy bath is not limited to the Russian capital, with thousands across the country taking the plunge.
Here on the Kamchatka Peninsula in the Pacific Ocean, hundreds wade into the sea.
(SOUNDBITE) (Russian) PETROPAVLOVSK-KAMCHATSKY RESIDENT, NO NAME GIVEN, SAYING:
"You come out of the water feeling purged. And it's warm, it's absolutely normal, and I have lost one of my slippers."
Some seem to enjoy the ritual more than others -- this little boy says, "I'm not going in there again!"
Russians who enjoy bathing in freezing water throughout the winter are given the nickname "morzhi", or walruses.
Nick Rowlands, Reuters.