thespleenandthemuse:

In Slavic mythology, a rusalka  was a female ghost, water nymph,succubus or mermaid-like demon that dwelled in a waterway.

According to most traditions, the rusalki were fish-women, who lived at the bottom of rivers. In the middle of the night, they would walk out to the bank and dance in meadows. If they saw handsome men, they would fascinate them with songs and dancing, mesmerize them, then lead the man away to the river floor to his death.