The United Nations Decade of Ocean Science for Sustainable Development (2021–2030), coordinated by UNESCO’s Intergovernmental Oceanographic Commission (IOC), was launched to catalyse global cooperation in ocean science to support the 2030 Agenda, particularly SDG 14. Rooted in equity, inclusivity, and diverse knowledge systems, the Decade fosters co-designed, science-based actions through a broad collaborative framework without imposing new financial obligations on Member States. Its implementation relies on a multi-tiered governance structure and seeks to integrate ocean knowledge into policy to enable sustainable ocean management. At the initiative’s halfway point, the UNESCO-IOC Executive Council requested a Mid-Term Evaluation, managed by UNESCO’s Internal Oversight Service (IOS), to assess the Decade’s effectiveness, relevance, and coherence, and provide strategic recommendations for its future direction. The evaluation uses a utilization-focused, mixed-methods approach—including over 1,000 stakeholder consultations across 118 countries—supported by tools such as social network analysis and policy influence assessments. It is guided by a Theory of Change and aims to inform decision-makers and stakeholders at all levels, from global governance bodies to national committees and implementing partners.The UN Ocean Decade has achieved substantial progress as the largest coordinated global ocean science initiative, mobilizing over 4,500 institutions and nearly USD 1 billion in support for Decade Actions, with a strong foundation in inclusive and collaborative science. Key achievements include cross-sector partnerships, integration of diverse knowledge systems, youth engagement through ECOPs, global visibility via high-profile events, and early outcomes such as tsunami preparedness and marine science education. However, the Mid-Term Evaluation identified challenges across governance, resource mobilization, science delivery, UN engagement, inclusivity, communication, and monitoring. Limited coordination capacity, regional imbalances, underrepresentation of LDCs and SIDS, and uneven policy integration hinder the Decade’s full potential. Strengthening decentralized coordination, strategic partnerships, and resource mobilization—particularly from private and philanthropic sectors—alongside improved monitoring, outreach, and inclusivity are essential to maximizing impact. Moving forward, enhancing UN-wide collaboration, fostering local ownership, and positioning UNESCO-IOC for strategic leadership beyond 2030 are critical to advancing ocean science and achieving the Decade’s vision

IOS Publication also referred to as IOC/INF-1545 in the documentation of the A-33 Assembly.

A summary is available as working document IOC/33/4.8.Doc(2) for the A-33 Assembly. 

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