Gefjun is the Norse goddess said to have plowed the island of Zealand from Sweden. In accounts preserved by Snorri Sturluson, she asked the Swedish king Gylfi for as much land as four oxen could plow in a day and night. She then harnessed four enormous oxen—described as her sons by a giant—to the plow and tore a section of land from the Swedish mainland. The resulting hollow became Lake Mälaren, while the displaced land became Zealand, the large Danish island on which Copenhagen stands.
The story appears in both the Prose Edda and Heimskringla, linking Gefjun with plowing, land formation, fertility, and Denmark. Gefjun is also associated with virginity and foreknowledge, and some traditions say that unmarried women who died became her attendants.
A common mix-up is the spelling: Gefjun, Gefjon, and Gefion are variant forms of the same goddess. She is not Freyja, although scholars have examined possible connections between their names and functions.