The winter of the icebreaking season 2024–2025 was mild and the season lasted 153 days
Published 19.5.2025 15.34
The icebreaking season began at a fairly normal time of year, on 19 December 2024, with Kontio leaving for the Bay of Bothnia as the first icebreaker of the season. The last icebreaker to return to Katajanokka was Polaris, on 20 May 2025. Thus, the icebreaking season lasted a total of 153 days. In practice, no icebreaking took place in the Gulf of Finland, as there was hardly any ice there this winter.
The first assistance restrictions for the Bay of Bothnia entered into force, on 21 December 2024, one month later than in the previous year. The development of the ice coverage was similar to the average winter until the beginning of January. However, the development slowed down at the end of January, and during February, the increase in the area covered by ice was small due to severe winds and milder weather. The amount of ice at sea did not decrease, however, but instead, it accumulated off the ports of northern Bay of Bothnia and caused difficulties for shipping.
Ice coverage was at its largest on 22 February 2025, one week earlier than average. On that day, ice covered an area of 85,000 km2, which means that the winter is classified as mild. Of course, the extent of the ice cover does not indicate how difficult the conditions have been for merchant shipping. It is often the case that the severe winds of a mild winter pose greater challenges than the winters of extensive ice cover, during which long periods of freezing temperatures occur.
"The winter was windy and mild. With the exception of the Bay of Bothnia and the Northern Quark, there was little ice in the waterway areas. There were no icebreakers working in the Gulf of Finland. The last time there was so little ice in the Gulf of Finland was five years ago, i.e. during the icebreaking season 2019–20,” says Tuomas Taivi, senior maritime officer at the Finnish Transport Infrastructure Agency.
Five icebreakers were in operation during the season, ships were assisted 1,014 times
A total of five icebreakers were in operation in the Finnish sea areas during the season. Otso, Kontio, Sisu, Polaris and Zeus of Finland operated in the Bay of Bothnia. In addition, smaller tugs were used in assistance tasks in the Gulf of Finland on a couple of occasions.
At the end of December, a normal winter seemed possible. In early January, the ice coverage expanded in the northern parts of the Bay of Bothnia to the Raahe-Luleå line. In the middle of the month, the first high southwest wind weighed the ice mass onto the mouth of the Kemi and Tornio waterways. The same happened again in January. At the turn of February, the northeast wind drove almost all ice to Sweden. However, the wind turned nearly immediately to the southwest and weighed the ice again against the shores of Finland.
The Bay of Bothnia froze over, on 21 February 2025, after which southwest winds began again, and ice masses were pushed onto the shores of Finland once again. The ice situation remained like this for the rest of the season, and there was need for assistance in the area extending from Kalajoki to Tornio. The ice situation in the Gulf of Finland did not develop further. Only on the Hamina, Kotka and Loviisa waterways, there was ice that hindered merchant shipping a couple of times, but only for a very short period. In other words, no icebreakers were needed in the Gulf of Finland this winter.
During the season, the icebreakers accumulated a total of 572 operating days, almost exactly half of the previous year’s number. During the season, the icebreakers sailed a total of approximately 37,000 nautical miles (86,000 in the previous season), which is about 68,500 km or one and a half times around the globe. There were approximately 13,600 ship calls to ports under assistance restrictions.
During the season, a total of 1,014 assists were made in the sea areas (2,234 in the previous season), of which 135 involved towing (428 previous season).
The assistance restrictions were in effect in sea areas between 21 December 2024 and 18 May 2025. The preliminary figure for the vessels’ average waiting time was 4.8 hours. About 91.5% of all vessels were able to enter the ports with assistance restrictions without waiting.
The assistance restrictions determine which vessels are entitled to icebreaker assistance in Finnish ports. The assistance restrictions depend on the vessel’s ice class, engine output and size, as well as the prevailing ice conditions. cv
The Finnish Transport Infrastructure Agency is responsible for the public office duties and procurement associated with winter navigation, as well as for the national coordination, development and control operations.
Moren information:
Helena Orädd, Head of Unit, tel. +358 29 534 3321, [email protected]
Tuomas Taivi, Senior Maritime Officer, tel. +358 295 34 3328, [email protected]
Helena Orädd, Head of Unit, tel. +358 29 534 3321, [email protected]
Tuomas Taivi, Senior Maritime Officer, tel. +358 295 34 3328, [email protected]
