Suomen ympäristökeskus

Wreck of coastal defence ship Ilmarinen studied in the northern Baltic Sea


The marine research vessel Aranda's expedition is heading south of Utö this week. Experts from the Finnish Environment Institute, the Finnish Border Guard and the Finnish Heritage Agency are studying the coastal defence ship Ilmarinen's wreck, sunk in 1941, for a possible oil removal operation. It is estimated that the tanks of the wreck contain approximately 100,000 litres of light fuel oil. 

Coastal defence ship Ilmarinen, SA-kuva 1941. Photographer Vilho Heinämies.
Coastal defence ship Ilmarinen, SA-kuva 1941. Photographer Vilho Heinämies.

‘The Ilmarinen shipwreck is a significant environmental risk. If it started to leak oil, under typical wind conditions the oil would drift towards the Finnish coast and the Archipelago Sea. Leaking oil would be a danger to the marine environment’, says Project Manager Tommi Kontto from the Finnish Environment Institute. 

If a decision on a clean-up operation is made, it will be put out to tender and carried out in 2024. 

The wreck modelled for further action 

The Finnish coastal defence ship Ilmarinen sank after colliding with a mine. The ship's wreck lies at a depth of approximately 80 metres, partially submerged in the bottom mud. Working in this depth poses challenges to the studies. 

The purpose of the study is to prepare a 3D model of the wreck for further action and to find out how the oil could be emptied from the wreck. The modelling uses the hydroacoustic equipment of the marine research vessel Aranda, and the wreck will also be filmed using the ROV diving robot. 

Water and sediment samples will be taken around the wreck during the studies, but the wreck itself will not be touched. The wreck is covered by the guidelines on the sanctity of graves, which has been taken into account in the research plan. If a decision to empty the tanks is made in the future, the sanctity of the grave will be ensured during the operation. 

There are nearly thirty risky wrecks in Finland's territorial waters 

It is estimated that there are over a thousand wrecks in Finland's territorial waters. Many of them may contain significant amounts of oil or other environmentally hazardous substances. 

There are nearly 30 high-risk wrecks. They are typically about to rust through or located near important or sensitive nature sites. 

Renovation of wrecks is part of the water protection programme 

The studies of the coastal defence ship Ilmarinen are part of a project aiming to renovate wrecks to enhance water protection, which receives funding from the Ministry of the Environment's water protection programme. 

The organisation responsible for the project is the Finnish Environment Institute, and the Navy and the Border Guard are particularly involved in its implementation. The Finnish Environment Institute is responsible for monitoring and renovating wrecks that pose a risk of environmental damage. The Border Guard is responsible for rescue operations in the event of oil and chemical spills from vessels in Finnish territorial waters and the exclusive economic zone and coordinates preparedness for spills. The Border Guard is actively involved in supporting measures to reduce wreck leakage risks in a benefit-oriented manner in order to avoid long-term and costly response measures. 

So far, 4 wrecks have been renovated in the project examining the possibilities for wreck renovation and implementing the renovation of wrecks: dredger Veli off the coast of Hanko, dry cargo vessels Hanna-Marjut and Fortuna near Kihti, and the motor vessel Beatris near Iniö. The above-mentioned wrecks were emptied by the Navy with the support of other authorities. 

The water protection programme 2019–2023 is a significant investment in the protection of waters. Its goal is to achieve a good ecological status of the Baltic Sea and domestic lakes and rivers. The measures of the programme will reduce the nutrient loading of agriculture and forestry into waters, clean oil from shipwrecks, restore water systems and reduce harmful substances in urban wastewater. 

The results of the expedition will be discussed at a media event 

At the end of the expedition, Finnish Environment Institute will organise a media event on the expedition vessel Aranda on Friday 4 August at the Tammasaari pier in Salmisaari, Helsinki, at 1–2 p.m. Journalists are welcome to come hear about the expedition, see the vessel’s equipment, and interview researchers. 

Please register your participation by email to Communications Trainee Tytti Juusti at by 11 a.m. on Thursday 3 August. Coffee and light snacks will be served at the event, so please notify of any special dietary requirements. 



Media service at Finnish Environment Institute

Our Media Service provides information on research, helps journalists find experts for interviews and provides photos for media use.

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It is time to move beyond solving environmental problems one by one, to systemic sustainability transformations. The Finnish Environment Institute (Syke) contributes to building a sustainable society through research, information and services. The Finnish Environment Institute is a research institute with 700 experts and researchers located in Helsinki, Oulu, Jyväskylä and Joensuu.

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