Foreword

The ocean is the foundation of life on Earth. But its health is at grave risk as ecosystems and habitats approach or surpass critical tipping points. In the search for solutions, ocean science is indispensable. The third World Ocean Assessment offers the most comprehensive evaluation to date, providing Governments, institutions and the public with the evidence needed to shape coordinated, effective action.

Five years ago, the previous Assessment found persistent degradation of marine ecosystems. This third Assessment documents a deepening crisis, as climate change, pollution, overfishing and biodiversity loss put ocean systems under severe strain. Its findings demand urgent action, through stronger multilateral cooperation, greater ambition and decisions grounded in the best available science.

This Assessment comes midway through the United Nations Decade of Ocean Science for Sustainable Development and the United Nations Decade on Ecosystem Restoration. It takes stock of what we have learned, how far we have come and what more is needed to secure a healthy, resilient ocean for current and future generations.

The entry into force of the Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction in January 2026 marks a historic milestone for ocean stewardship and multilateral cooperation. Now we must translate that momentum, and the latest science, into decisive action for a healthy and resilient ocean.

May this Assessment strengthen our resolve to protect the ocean and, in doing so, help safeguard our climate, our food systems, our prosperity and our future.