What lies on the bottom of the Baltic Sea? Maritime Office reveals hazards

Shipwrecks with fuel-filled tanks, corroded bombs, and remnants of chemical weapons are among the most problematic findings resting on the bottom of the Baltic Sea. During a conference held on 15 June 2026 in Gdynia, the results of the latest environmental studies and recommendations for neutralizing these and other hazards were presented.

Environmental hazard identification in the Baltic Sea

The project Identification and possible neutralization of hazardous materials lying on the bottom of the Baltic Sea in selected locations is being carried out by the Maritime Office in Gdynia, among others with funding from the National Recovery and Resilience Plan (NRRP). The research budget amounts to nearly PLN 150 million, with almost 20 percent coming from state funds.

Ultimately, the project envisages the preparation of a detailed report on the condition of the marine environment, but advanced research work is still underway. Scientists are conducting extensive hydrographic and chemical analyses using samples of seabed material, sediments, and water. The key objective is not only to identify and precisely locate hazardous materials on the Baltic seabed, but also to assess their potential impact on the marine ecosystem.

Today, we know that although remnants of World War II still require monitoring and responsible management, the environmental situation is not as alarming as earlier catastrophic scenarios suggested. The project has provided data that will enable a systematic approach to risk assessment and the planning of future actions, said Jan Młotkowski, Deputy Director of the Maritime Office in Gdynia for Navigational Marking, while summarizing the project’s initial results.

Franken and Stuttgart: the most dangerous wrecks on the Baltic seabed

The German tanker T/S Franken, sunk in April 1945, rests several nautical miles from the Hel Peninsula. It is one of the most concerning wrecks on the Baltic seabed. The reason is the large volume of fuel, estimated at between 1.5 and 5 million litres, still contained in its corroding tanks. Research conducted by the Maritime Office in Gdynia showed that the situation remains stable. Seabed sediments are not contaminated with hydrocarbons, and elevated concentrations of hazardous substances are localized. Researchers recommend continued monitoring of the wreck and its surroundings, noting that scattered conventional ammunition has been discovered nearby.

The wreck of the hospital ship SS Stuttgart, sunk at the entrance to the Port of Gdynia, requires intervention. Contamination of the seabed with heavy fuel oil rich in mercury, manganese, and copper has been confirmed in the area. Scientists conducting the research suggest removing accumulated fuel deposits and/or applying natural remediation methods using zeolites.

Hazards in the Słupsk Furrow and Gdańsk Deep areas

In addition to the wrecks mentioned above, the Maritime Office’s research also covered two other locations where hazardous substances have been identified. Both the Słupsk Furrow and the Gdańsk Deep areas contain a number of concerning materials, including:

• remnants of chemical weapons;

• corroded and leaking aerial bombs, mines, and barrels;

• decomposition products found near wrecks and ammunition casing fragments.

Unfortunately, according to experts, the technical condition of the identified objects does not allow for their removal. Recommendations for further action have been included in Hazard Neutralization Plans prepared for each of the studied areas. Following final verification, the documents will be published on the website of the Maritime Office in Gdynia.