The Global Ocean Observing System (GOOS) is a global system for sustained observations of the ocean comprising the oceanographic component of the Global Earth Observing System of Systems (GEOSS). GOOS is administrated by the Intergovernmental Oceanographic Commission (IOC), and joins the Global Climate Observing System, GCOS, and Global Terrestrial Observing System, GTOS, as fundamental building blocks of the GEOSS.