Sjöjungfru
Sjöjungfru (Lake Maid) is a Swedish freshwater spirit, a beautiful woman with long wet hair who dwells in deep lakes. She emerges to sing, can grant fishing luck or cause drownings, and may form relationships with land-dwellers. Distinct from the marine havsfrú (Sea Lady) and the more dangerous sjörå. Documented in Swedish folklore collections and place-name legends. The term means 'lake-lady.'