Viruses, the smallest and most numerous of all biotic agents, represent the planet’s largest pool of genetic diversity. The sheer abundance of oceanic viruses results in B1029 viral infections per day, causing the release of 108–109 tonnes of carbon per day from the biological pool (Suttle, 2007). Still, how and to what extent virus-mediated nanoscale processes are linked to global-scale biodiversity and biogeochemistry is poorly defined. Recently, two international panels—the EUR- opean network of excellence for OCean Ecosystem ANalysis (EUR-OCEANS) Marine Virus Workshop and the Scientific Committee for Oceanographic Research working group on marine viruses (SCOR WG126) brought together international scientists to focus on these issues and to identify future direc- tions in marine virus research by defining important questions (EUR-OCEANS) and potential practical approaches (SCOR). The present commentary high- lights open questions in marine viral ecology and illustrates how fusions between (meta)genomics and geochemistry may decipher the role of viruses in global-scale processes. ; 4 pages, 1 figure.-- Full-text version available Open Acces at: http://icm.csic.es/bio/projects/icmicrobis/