Multilateral consensus forged among heads of states must be value-additive and relevant at the national level to facilitate on-ground implementation. Yet, despite general optimism and advances in policy understanding, multi-scale diffusion remains a challenge with little certainty in outcomes. This study focuses on examining intermediary dynamics occurring within national policy apparatus that can influence domestic uptake of policy innovation. We analyse the anticipated spread of two supranational policies on coastal fisheries in the Pacific region – the 'small-Scale Fisheries Guidelines’ and ‘the New Song’ – in three countries: Kiribati, Solomon Islands and Vanuatu. Our approach combines instrumental perspectives on ‘policy coherence’ with cognitive–normative perspectives on ‘policy image’. Accordingly, we use two methods: a document-based comparison of the policies produced at different levels and interviews with national government officers in charge of policy deliberation and delivery. We find supranational-to-national policy coherence across most prescribed policy themes, except for emergent social themes such as ‘gender’ and ‘human rights–based approaches’. The views of government managers substantiate, and further augment, this finding. Crucially, managers' images (encompassing judgements, aspirations and convictions) represent personal and practical attributes involved in policy interpretation and implementation. Multi-scale policy diffusion is thus a translational process mediated by national-level staff, and managers' policy images offer nuanced and dynamic insights into why some policies are slow to take root while others take different shape to their agreed meanings. Analysts and policymakers must consider and mobilise translational approaches and policy images in order to understand and facilitate successful domestic implementation of international agreements.