Never before has so much ice built up so late in the year on the Baltic Sea and in Gulf of Bothnia between Sweden and Finland -- and records have been kept for 50 years, according to Swedish news agency TT.
"We have never seen anything like this," says icebreaking manager Ulf Gulldne, to the Swedish newspaper Örnsköldsviks Allehanda. A stubborn area of high pressure camped over Scandinavia has contributed to freezing temperatures late in the winter and to the new record.
On March 29, some 176,000 square kilometers of the Baltic were covered by ice. The previous record came in 2008, when just 49,000 square kilometers of sea ice were recorded as late as March 25.
Half of the Gulf of Bothnia, including the central and northern sections, is also ice-covered. And the farther north one goes, the thicker the ice gets, making it difficult for ships to navigate. Because of that, five icebreakers are working the area. They helped clear the way for 465 ships last week, a weekly record this winter.
But there is still ice cover even as far south as the Stockholm archipelago and half of Lake Vänern is still covered in ice.
"We're talking about unusually cold weather, normally the ice has already begun to melt," says Torbjörn Grafström, at the Swedish Meteorological Institute.
Meteorologists expect the ice to completely melt by the end of May.