The Ilmarinen shipwreck is being investigated to avoid potential oil spills

The Ilmarinen wreck contains light fuel oil and poses significant risks to the marine environment. On 13 September 1941, coastal defence ship Ilmarinen sank in the northern Baltic Sea, about 40 kilometres south of the island of Utö, after hitting a mine. The wreck is located at a depth of approximately 80 metres. Its tanks contain an estimated 100,000 litres of light fuel oil.

“Removing the oil from Ilmarinen will protect the Baltic Sea by reducing the risk of oil spills from the wreck. At the same time, we will strengthen the expertise of the authorities and other actors in cleaning up shipwrecks. There are almost thirty shipwrecks in Finland’s territorial waters, which are a risk to the environment,” says Minister of the Environment and Climate Change Kai Mykkänen.

The Finnish Environment Institute collaborated with the Finnish Border Guard and the Finnish Heritage Agency to conduct the first preliminary investigations on the Ilmarinen wreck a year ago, in August 2023. According to the investigation, the Ilmarinen wreck is well preserved, but particularly its surface shows significant changes caused by corrosion. Oil droplets were found to rise regularly from the wreck.

According to project manager Tommi Kontto from the Finnish Environment Institute, the risk assessment of the sunken vessel was updated on the basis of last year’s investigations. It is estimated that the wreck poses a significant risk to marine life and the environment in the event of an oil leak. The Archipelago National Park is located near the wreck. The winds and currents prevailing in the area are likely to carry a potential oil spill towards the national park.

Further investigations on Ilmarinen

Investigations into the Ilmarinen wreck will continue on the multipurpose vessel Louhi between 12 and 18 August 2024. Among other things, material thickness measurements will be conducted on the wreck in order to better assess its current condition and to plan the removal of the oil in more detail. Furthermore, additional images of the sunken ship will be captured with the help of divers and an underwater robot. The image material will be used to construct a photogrammetric model.

The Finnish Environment Institute is conducting the research in collaboration with the Finnish Border Guard and the Navy.

“Research dives to the sunken coastal defence ship are highly demanding, and the collected data will facilitate the future clean-up of the wreck. Thanks to the cooperation between the authorities, we are able to efficiently perform such diverse operations in the maritime environment,” says Commodore Marko Laaksonen, Head of Operations at the Navy.

The Finnish Environment Institute invited bids for the clean-up of Ilmarinen’s wreckage last February with the intention of emptying the wreck’s oil tanks during 2024. However, no suitable contractor was found through the tendering process. Working together with other authorities, the Ministry of the Environment supports the removal of oil from the shipwreck as work carried out by the authorities. The goal is to extract the oil from the sunken vessel in 2025. The removal of oil from the wreck is funded by the Ahti water protection programme of the Ministry of the Environment (2023–2027).