The vodyanoi is an unfriendly creature who lives in a crystal palace at the bottom of a river, lake or sea.
He decorates his home with treasures from sunken ships, and he dislikes human beings so much that he drowns them or makes them his slaves, giving them the ability to live underwater too.
It is said that he is only seen or heard at night. He sometimes looks like a large fish and sometimes like an enormous frog, as large as a seal, with a human face. He is blamed for breaking dams to let the waters flow.