The National Science Foundation's Ocean Observatories Initiative Regional Cabled Array is transforming how scientists, educators and the public observe and interact with the ocean. This underwater cabled observatory brings the Internet into the ocean through use of high power and bandwidth fiber optic cables that provide abundant power and two-way, interactive communications to novel sensor arrays on the seafloor and throughout the water column. The observatory includes six state-of-the-art instrumented, full water column moorings (up to 2900 m, >9500 ft water depth) hosting instrumented wire crawlers, winched science pods, and platforms to study linkages among physical, biological and chemical processes spanning blue water to coastal systems along the Cascadia Margin. The coastal array is located at highly productive coastal sites strongly impacted by the California Current, upwelling, ocean acidification, and hypoxia events. The network also includes cutting edge seafloor sensors focused on understanding active volcanism, life in extreme environments, seismicity, and biogeochemical processes and fluxes in actively forming gas hydrate systems. Two-way 24/7/365 communication with direct connection to the Internet, with expansion up to 240 Gb/s and high power (8 kW), allow highly interactive, rapid responses with adaptive sampling to events such as formation of thin layers, large storms, internal waves, volcanic eruptions, and earthquakes.