60,000 litres oil removed from 85-year-old sunken ship Ilmarinen

The Finnish Environment Institute (SYKE) and the Finnish Navy removed about 60,000 litres of oil from the wreck of the coastal defence ship Ilmarinen between 14 and 24 July, said the SYKE and Ministry of the Environment on Friday.

The Finnish Border Guard prepared for environmental response operations, and the Diving Medical Center participated in the operation.

The emptying of the Ilmarinen’s tanks, which began in mid-July, went well even though not all of the oil could be recovered yet

Because of the rough seas, the work had to be interrupted from time to time.

The coastal defence ship Ilmarinen, which sank off the island of Utö during World War II, is one of the shipwrecks that are hazardous to the Baltic Sea environment. The environmental risk is posed by the oil in the vessel’s fuel tanks, the amount of which is estimated to be about 100,000 litres in total.

“The operation as a whole was successful, even though we had to interrupt our work for three days because of the rough seas and retreat to the archipelago for shelter. The operation also had to be finished approximately one day earlier than planned because of the roughness of the sea,” said Project Manager Tommi Kontto of the SYKE.

“Considering this, we worked quite efficiently. Oil was removed from the tanks on the bow side of the Ilmarinen, and the risk of a major environmental accident caused by the possible collapse of the bow could be reduced significantly,” Kontto said.

According to Commander Toni Joutsia, Chief of Staff of the Coastal Fleet, the operation was an extremely demanding task.

"There is 60–80 metres of water at the site where the Ilmarinen sank. It sets very strict safety requirements for the equipment, the diving activities and the operations on the surface. The Ilmarinen lies upside down on the seabed, its keel towards the surface. We were able to pump oil directly from the tanks through the holes we had drilled to the bottom of the vessel,” said Commander Joutsia.

It is estimated that 40,000 litres of oil still remains in the wreck of the Ilmarinen. The aim is to continue the work in 2027.

The wreck of the coastal defence ship Ilmarinen is located in the northern Baltic Sea, outside the territorial waters in the exclusive economic zone of Finland.

Ilmarinen sank in September 1941 after having hit a sea mine.

A total of 271 crew members drowned with the vessel and the wreck is their final resting place. Preserving the sanctity of the grave has been an important aspect of the operation.