An international team has conducted the first-ever global survey of the ecological diversity of viruses in the oceans during expeditions aboard a single sailboat, the Tara. They identified nearly 200,000 marine viral species, which vastly exceeds the 15,000 known from prior ocean surveys of these waters and the approximately 2,000 genomes available from cultured viruses of microbes. Their findings, appearing April 25 in the journal Cell, have implications for understanding issues ranging from evolution to climate change, because they help create a new picture of our planet and how it may be impacted by interactions among organisms.