Understanding climate means first understanding the oceans. Given the highly stressed conditions of coastal areas, our understanding now just skims the surface. As a major shift in the approach to ocean observing, the Integrated Ocean Observing System (IOOS®) is bringing together many disparate systems to produce the continuous data essential to making informed decisions about America’s oceans, coasts and Great Lakes. The aim is to build the national infrastructure needed to respond to climate variability and other events. Complementing this effort, the Ocean Observatories Initiative (OOI) is conducting research designed to deepen our understanding of the oceans and lead to new and improved technologies. By enabling access to long-term ocean and seafloor measurements, for example, OOI will investigate how seafloor seismic readings can provide early warnings of the undersea earthquakes preceding tsunamis.