Gefjon or Gefjun (“the giver”) was a goddess in Norse mythology.
In the 13th century, Snorri Sturlason retold the story of Gefjon like this:
"Then he (Oden) went north to the sea and settled on an island. There it is now called Odensö on Funen. Then he sent Gefjon across the strait to look for land."
The same author recounts the episode in a different way in the part:
"How Gylfe was deceived" in Snorre's Edda:
"King Gylfe ruled over the lands now called Svitjod. It is said of him that he gave a wandering woman a plowland as thanks for the joy she gave him. It would be as large as four oxen could plow up in a day and a night. But the woman was of the family of the Aesir. She fetched four oxen from Jotunheim in the north, and they were her sons, and put them to a plough took so strongly and deeply that the land was cut off, and the oxen dragged that land westward into the sea and stopped in a strait. There Gefjon settled the land and named it Zealand." It is also said that Odin gave his son Shield to Gefjon as a thank you. They settled in Lejre and formed Denmark's first royal dynasty, according to the legend.