Gandvik

In Norse mythology, Gandvik is a dangerous sea, known as 'Bay of Serpents' because of its tortuous shape. Saxo Grammaticus stated that Gandvik was an old name for the Baltic Sea (a name misspelt Grandvik in some translations). The legend presumably refers to Gulf of Bothnia. However, there are two opposite theories about where Gandvik was situated, based on the peace treaty in Nöteborg 1323: in the Arctic Ocean or the Gulf of Bothnia. Starting from 1850s, the former received more support in that Sweden had extended far out to the Arctic Ocean, but since the 1920s the latter have gained more support. However, Hversu Noregr byggdist, dating from the former part of the 13th century, is by most opinions referring to the White Sea when it uses the term Gandvik. (LUNDKVIST 1985)

Source: "Northern Scandinavia during the Middle Ages", part of "In honorem Evert Baudou" (1985), Sven Lundkvist