The One Ocean Science Congress 2025, organized by the French National Centre for Scientific Research (CNRS) and the French Research Institute for Exploitation of the Sea (IFREMER), took place from June 3 to 6 in Nice, France. Held just ahead of the Third United Nations Ocean Conference (UNOC3), the congress brought together over 2,000 scientists, researchers, and ocean experts from around the world to address urgent challenges facing our oceans, including climate change, pollution, overfishing, and maritime governance.

The four-day program featured plenary sessions, keynote speeches, oral and poster presentations, and interactive townhall meetings that fostered dialogue between science, policy, and society. Discussions spanned ten thematic areas aligned with the UN Decade of Ocean Science for Sustainable Development, covering topics such as marine genetic resources, illegal fishing, plastic pollution, and the decarbonization of maritime transport.

Insights and recommendations from the congress aim to inform global policy discussions at UNOC3 and contribute to the development of the Nice Ocean Action Plan—reinforcing the integration of scientific research into sustainable ocean management and supporting the achievement of Sustainable Development Goal 14: Life Below Water.