The Intergovernmental Oceanographic Commission of UNESCO organizes for the first time an Ocean Science Day prior to a session of its Assembly, the governing body of the Commission. The Assembly sessions gather every two years IOC Member States (147 at this date) and partner organizations. The objective of the Ocean Science Day is to further increase the visibility and understanding of ocean science, current challenges and emerging issues. The Ocean Science Day roots in the importance of the role of science and scientists for sustainable societies and in the need to inform and involve decision-makers in science. The event provides an opportunity to show the relevance of ocean science for the sustainability of our planet and to engage the decision-makers in discussions. We believe this also offers a good opportunity for the marine scientific community to discuss on prospects on ocean science with colleagues and also with a wide representation of national stakeholders and Member States representations in UNESCO. The Ocean Science Day intends to focus on emerging issues that require international collaboration in marine science and technology. It also highlights the need to produce new ocean science and technologies for the benefit of society. In consultations with the Officers of the Commission, this year’s scientific programme is organized around four themes: - Oceans, Health and Wellbeing (IOC Anton Bruun Memorial Lecture, 2015); - Glider challenge: High resolution for 4D oceanic measurements; - International expeditions: From the Indian Ocean to the World Ocean and back in 50 years (IOC N.K. Panikkar Memorial Lecture, 2015); and - The scientific challenges in the Arctic We would like to thank our speakers for their availability and enthusiasm and we hope that you will enjoy the lectures and the panels. Questions can be sent by email before and during the event only at the following temporary email address: iococeanday2015@unesco.org Find more on the dedicated webpage.