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. Sometimes magical tricks, and even dead man's hand, were required as well, to uncover the treasure. In Finland and several other northern countries, it was believed that early autumn was the best time to search for will-o'-the-wisps and treasures below them. It was believed that when someone hid treasure, in the ground, he made the treasure available only at the Saint John's Day, and set will-o'-the-wisp to mark the exact place and time so that he could come to take the treasure back. For then he could be fulfilled with treasures.