More than 20 years ago, the discovery of billions of viruses in the oceans was big news, worthy of articles in Nature1 and on the front page of the Washington Post. A year later another Naturereport was published, this time about the most abundant bacterial group in the oceans, cryptically called SAR11. The two stories now come together in a paper published on Nature's website today. Zhao et al. describe DNA viruses that they call 'pelagiphages' and which infect laboratory-grown representatives of SAR11 bacteria. The authors use genomic-sequence data to argue that pelagiphages are among the most abundant viruses in the oceans and perhaps the entire biosphere. The report ends long-running speculation about SAR11, but prompts new questions about marine viruses and the control of microbes in the oceans.