Ivan Kupala is a traditional Slavic holiday that was accepted into the Orthodox Christian calendar. The celebration relates to the summer solstice when nights are the shortest, festivities take place the night of July 6th/7th (new calendar) and includes a number of Pagan rituals.
Enthusiastically celebrated by youth, the holiday is marked with water fights (connected to ritual purification), jumping over bonfires (fire signifying the burning of illness and evil forces) and unwed women floating flower wreaths.
On Kupala night mermaids leave lakes and rivers, so You can swim safely. Peasants believed that on Ivan Kupala night they should not sleep, because all the evil spirits were awakened – witches, werewolves, mermaids, snakes, warlocks, mermen and woodland spirits.
The celebration also includes circle dances, singing folk songs, searching of the magical fern flower, playing games.
https://go-to-russia.ru/index.php/about-russia/holidays-and-events/292-7-july-ivan-kupala#sigProId0b7509c44d
