Limfjord is a shallow area of the sea that cuts across the Jutland Peninsula, between the Kattegat and the North Sea, separating the northern portion into an island. It is not a fjord in the geologic sense, although it has been considered as such by the Danish since Viking times. It is 112 miles long, winding and narrow with many bays and islands. The large Danish city of Aalborg is located on the Limfjord.