The Finnish Environment Institute and the Finnish Navy have removed approximately 60,000 litres of fuel oil from the wreck of the coastal defence ship Ilmarinen, which sank in 1941.
The operation, conducted earlier this month, marks a significant step in mitigating environmental risks associated with the historic vessel.
An estimated 40,000 litres of fuel oil remain to be recovered.
Authorities have scheduled a planned follow-up operation for next year to complete the extraction process.
The Ilmarinen, a key part of Finland's naval history, has long been a focus of environmental monitoring due to the potential for fuel leakage from its submerged hull.
The cleanup effort underscores the ongoing challenges of managing historical maritime hazards.