Environmental impact assessment (eia) and strategic environmental assessment (sea) are procedures for the prior assessment of impacts of proposed developments before decisions are taken. Customary law and most international agreements relevant for the Arctic Ocean are unspecific about assessment tools and content. The Espoo Convention and its sea Protocol are the only specialised instruments available. They do not cover marine activities well, and not all the Arctic Ocean coastal states are parties. Other problems in the assessment regime are related to uneven geographical and sectoral coverage. Weaknesses may be addressed both globally in the negotiations on a new instrument under the Law of the Sea Convention (losc) on biodiversity beyond national jurisdiction, and in a regional process under the Arctic Council. Important improvements would be the creation of a more specific default mechanism for prior assessment of marine activities and closer linkage of assessments with substantive goals.