With meteorological agency SMHI forecasting more cold weather for the coming weeks, the big freeze seems set to stay.

Even Skagerrak, Kattegat and Öresund, waterways off the west and south-west coasts that are generally spared the ice treatment, risk freezing over as the cold snap continues.

“At the moment it’s so gusty that new ice hardly has time to settle. But the waters have really cooled down, so if the wind eases off it could happen quickly,” said Johny Lindvall, deputy head of shipping at the Swedish Maritime Administration (Sjöfartsverket).

Six of the agency’s seven icebreakers have already been put to work, with the seventh, Ymer, ready for action at the end of the week. One of the icebreakers, Ale, is currently assisting in the northern Kvarken area in the Gulf of Bothnia but may be redirected to Lake Vänern should the need arise.

The last time the Gulf iced over so far south was in 2006 when the freeze stretched as far as Oskarshamn and the Swedes enlisted the help of their Danish neighbours, whose icebreakers had remained quayside for the previous fifteen years.

“We leased their icebreaker Danbjörn,” said Johnny Lindvall.

“They were very enthusiastic. We called on a Friday and the Danbjörn arrived at Oskarshamn on the Tuesday. The only thing was that none of those on board had ever been out in the ice before, not even the captain. So we had to put an old icebreaker captain on board as supervisor. But then everything went fine,” he added.