This Conference report provides a summary of the main highlights and key messages delivered by the speakers and chairs at the EurOCEAN 2010 Conference. The overarching recommendations from the Conference are summarized in the Ostend Declaration which calls for the recognition that “The Seas and Oceans are one of the Grand Challenges for the 21st Century”. The declaration states that the European marine science research community stands ready to provide knowledge, services and support the EU, and its Member and Associated States, to address critical marine and maritime challenges and opportunities which can, in turn, directly contribute to solving some of the most pressing societal challenges facing Europe and the worldtoday.The full text of the Ostend Declaration is included at the beginning of this report. Further information on the EurOCEAN 2010 Conference - including the Ostend Declaration in all official EU languages - is available at: www.eurocean2010.eu