The Ocean Observatories Initiative (OOI) is a National Science Foundation (NSF) Major Research Facility composed of a network of science-driven ocean observing platforms and sensors (ocean observatories) in the Atlantic and Pacific Oceans. This networked infrastructure measures physical, chemical, geological, and biological variables from the seafloor to the sea surface and overlying atmosphere, providing an integrated data collection system on coastal, regional and global scales. OOI's goal is to deliver data and data products for a 25-year-plus time period, enabling a better understanding of ocean environments and critical ocean issues.