The Marine Geoscience Data System (MGDS) is a trusted data repository that provides free public access to a curated collection of marine geophysical data products and complementary data related to understanding the formation and evolution of the seafloor and sub-seafloor. Developed and operated by domain scientists and technical specialists with deep knowledge about the creation, analysis and scientific interpretation of marine geoscience data, the system makes available a digital library of data files described by a rich curated metadata catalog. MGDS provides tools and services for the discovery and download of data collected throughout the global oceans produced primarily by National Science Foundation (NSF) supported researchers, and is the recommended data repository for NSF-funded Marine Geology and Geophysics projects. MGDS is designed to serve the needs of the science user community with a focus on (1) enabling data discovery and access, (2) curating coherent disciplinary collections of data that facilitate the creation of global syntheses, (3) ensuring the long-term preservation and stewardship of research data products, and (4) facilitating compliance with data management and data sharing obligations. MGDS directly complements data stewardship activities of the allied NSF-funded Rolling Deck to Repository (R2R). In addition, MGDS coordinates with and leverages the NOAA National Centers for Environmental Information (NOAA NCEI) for the integration of data into the national long-term archive and for redundancy storage of large-volume data.