This weekend, tens of thousands of Russians will plunge into freezing rivers and lakes to celebrate the feast of the Epiphany, known as Kresheniye in Russian.

For Orthodox Christians, the day celebrates the baptism of Jesus in the Jordan River, and a dip into blessed waters is said to cleanse the faithful of sins and purify the spirit. But it’s not just Orthodox Russians who will take the plunge — the celebration has also become popular among non-believers, who maintain that a quick ice bath is good for your health.

The religious holiday will be celebrated on Saturday, Jan. 19, but the first bathers can take the plunge on Friday night according to tradition. In Moscow, Saturday’s forecast predicts temperatures falling below -6 degrees Celsius. For many foreigners, the prospect of doing anything in this weather other than hiding under a pile of blankets can seem daunting. But for those brave enough to put themselves to the test, here are a few tips for staying safe and healthy during the Epiphany festivities.