North Sea
The border between the North Sea and the Skagerrak is at an imagined line between Lindesnes in Norway, and Hanstholm in Denmark. In the North, the North sea is open towards the Atlantic. The border between the two is an imagined line from Northern Scotland, to Shetland, and then to Ålesund in Norway. According to the Oslo-Paris Treaty of 1962 it is a bit more to the west and the north though. The treaty puts it at 5° East longitude, and 62° North latitude. That is at the parallel of the Geirangerfjord in Norway.