Warmer ocean temperatures are leading to expanding oxygen loss within Earth’s oceans, negatively impacting global fisheries. Microbial processes exacerbate ocean deoxygenation and in low oxygen conditions facilitate the production of gases, including nitrous oxide and methane, that can have feedbacks on atmospheric and ocean chemistry. Despite the significant role of microbes, little is known about controls on microbial processes within oxygen-depleted marine waters, including the impact of viral infection. Such information is critical to accurately forecast the impact of ocean deoxygenation. This project uncovers previously undiscovered populations of RNA viruses present and active within marine oxygen-depleted systems and connects them to hosts through leveraging a one-of-a-kind collection of microbial and viral samples sourced from three of the largest marine oxygen-depleted systems on Earth. The project incorporates immersive educational programs into the research workflow through undergraduate internships leading to co-authorship on scientific manuscripts and presentations at scientific conferences. Student interns are gaining valuable experience carrying out research that involves learned skills in coding, data science, genomics and molecular biology, skills required for future careers in biotechnology and forecasting. This project applies state-of-the-art computational workflows and develops new techniques to discover and characterize RNA viruses within a multidim