Marine-based CDR (mCDR) has substantive technical potential to sequester CO2 at gigatonne scale. Some techniques also have co-benefits such as addressing ocean acidification, enhancing biodiversity as well as generating negative carbon building materials. The focus of CDR policy in two pioneer nations that are seeking to establish, develop and scale CDR to 2050 – the US and UK – have very much posited their innovation policy on terrestrial based CDR value chains. The US is now ramping up substantive research programmes in this area. The UK is still very much focusing its CDR policy on terrestrial-based technologies with the establishment of a 100MtCO2 pa CDR sector in the UK by 2050; this will have a non-trivial land footprint. There is a need, therefore, to consider the potential role and optionality that mCDR has with regards to UK net zero policy to 2050 and how this might be accommodated for to keep this option open should it prove efficient and scalable. As part of its work on market transition risk, CO2RE held two sessions with stakeholders to explore what needs to be in place for mCDR to scale sustainably in the UK. This document presents the findings from those sessions.