The collective shaping power of marine microbes is immense, from the sea surface microlayer to the geological depth of marine sediments. Looking in more detail, marine microbes are compellingly interconnected with their physicochemical environment, with kindreds and other (micro)organisms. They live an interdependent and intertwined life, persist and (co)evolve under challenging and changing conditions. Despite their acknowledged ecological importance, there is still limited understanding of the physiological and genetic mechanisms that govern the biogeochemical processes carried out by microbes in the sea. The current Marine Microbes Research Conference – “The Interconnected Microbial Ocean” – aims to highlight from a cross-disciplinary perspective, the vital functional roles of microorganism in the different, complex marine ecosystems. In the spirit of GRC, it will emphasize inspiring presentations and open discussion of pioneering, unpublished research and state-of-the-art approaches, in a collaborative and interactive atmosphere.