In European folklore, these lights are believed to be spirits of the dead, fairies, or a variety of other supernatural beings which attempt to lead travelers to their demise.
Danes, Finns, Swedes, Estonians, Latvians, Lithuanians and Irish people and amongst some other groups believed that a will-o'-the-wisp also marked the location of a treasure deep in ground or water, which could be taken only when the fire was there.