To limit global warming, greenhouse-gas emissions need to be reduced drastically. To balance hard-to-abate emissions, a range of marine carbon dioxide removal (mCDR) approaches are envisaged. They can also contribute to Nationally Determined Contributions (NDCs) – most specifically as part of the Blue NDC Challenge – and other goals addressed at COP30. The event discusses potentials of selected mCDR approaches as well as research needs and key requirements for a responsible implementation.