Synthesizing stakeholder knowledge on submerged munitions in the Baltic Sea: Insights from World Café and Mentimeter engagements

A legacy of submerged munitions remains in European seas decades after the World Wars. This poses significant ecological, security, safety and socio-economic risks to marine biota and humans. This underscores the need for immediate remediation. To synthesize current knowledge, identify gaps and challenges in the risk assessment, and legal frameworks for marine munitions; a stakeholder workshop was held during the Kiel Munition Clearance Week conference (Germany). We used two approaches: the World Café method and Mentimeter - a digital responses tool. Our findings indicate that most stakeholders were concerned about the impacts of marine munitions on the environment, as well as critical infrastructure, security, and safety. Consequently, they indicated that the key criteria for prioritizing remediation should be environmental impacts, presence of critical infrastructure, social well-being, security, and munition casing corrosion. Although the stakeholders indicated that environmental impacts should ideally drive remediation actions, they noted that actions are likely more feasible when justified by the risk to critical infrastructure and security, as these impacts are immediate and visible than ecological impacts. Additionally, the stakeholders identified critical knowledge gaps in national and EU legislative frameworks, environmental impact assessment, and remediation cost. The gaps, knowledge, and stakeholder perspectives synthesized in this study could provide lines of evidence to guide responsible authorities and agencies on what to prioritize and address for effective remediation of munitions in European marine waters. These insights are also relevant to the EU Oceans Pact, 2025, aiming to provide a unified framework for remediating munitions.