They did. The main source of Swedish iron ore was the major mines around Kiruna in the far north of the country. A railway line linked this to the nearby port at Lulea on the Baltic. Ships could then take this to Germany or any other destination - but only in summer. The Gulf of Bothnia, the arm of the Baltic between Sweden and Finland, freezes in winter. In the winter months, usually between November and April, Lulea was icebound and could not be reached by ship. Another route was needed. To build a railway from Kiruna to the southern parts of the country where the Baltic stayed ice-free year-round would have been prohibitively expensive, especially since it would run through poorly developed, heavily forested rugged country. It was much cheaper to run the railway to the much closer Norwegian port of Narvik, which was always ice-free. In 1939, Sweden exported 9,981,000 tons of iron ore to Germany. Of these, 4,027,000 tons was exported through Narvik, leaving 5,984,000 tons to be shipped through the Baltic. In 1940, after the Royal Navy largely closed down exports from Narvik, Sweden exported 8,170,000 tons of ore to Germany, with only 504,000 tons going through Narvik.

The port of Luleå was closed during the winter because of the Ice until the 1970's with the Atle class icebreakers made it possible to break the ice year round.

But during the war Germany pressured Sweden to use Swedish vessels for the Iron ore and during that time they traveled between Luleå and Rotterdam in the North Sea. This was because if the ship was lost it wasn't a german vessel so they didn't care and in Rotterdam they could transload unto Rhine barges and not use the overworked rail network into the Ruhr from the Baltic Ports.