The Global Ocean Observing System (GOOS) is a sustained collaborative system of ocean observations, encompassing in situ networks, satellite systems, governments, UN agencies and individual scientists. We are organized around a series of components undertaking requirements assessment, observing implementation, innovation through projects, and a core team. GOOS utilizes the Framework for Ocean Observing to guide its implementation of an integrated and sustained ocean observing system. This systems approach, designed to be flexible and to adapt to evolving scientific, technological and societal needs, helps deliver an ocean observing system with maximized user base and societal impact. In fact, the Framework guides the path from the science-driven requirements resulting from societal issues, identifying the observations deployment and maintenance needed for the production of impactful and relevant tools to address those issues. To maintain an ocean observing system that is fit-for-purpose, the outputs (publications, products, ocean services) must properly address the issues that drove the original requirements. This system evaluation creates a constant feedback loop such that requirements are always science-driven and informed by societal needs.