Prior to the emergence of underwater cabled observatories, oceanographers and other researchers studying the global ocean tended to rely on the use of research vessels and manned submersibles in order to collect data.  This was followed by a shift toward Remote Operated Vehicles (ROV's) and space-based research satellites.  The limitation to these methods was that they were either not cost-effective, or data could only be collected for short durations.  While the importance of expedition-based exploration was recognized, a solution was needed.
In 1987, the concept of utilizing high-power, high-bandwidth underwater cabled observatories emerged as a long-term, cost-effective solution for conducting real-time monitoring of ocean systems.
In the early 1990s, the United States and Canada formed an agreement to develop a plate-scale submarine electro-optically cabled ocean observatory in the northeast Pacific Ocean.  This region is home to the smallest of Earth's tectonic plates – the Juan de Fuca plate.  The small size and close coastal proximity of the Juan de Fuca plate presents a unique opportunity to observe the dynamic systems in submarine volcano regions.
The partnership between the U.S. and Canada developed into a plan to build a Canadian cabled array that would cover the upper 1/3 of the Juan de Fuca plate, and a U.S. system spanning the lower 2/3 of the plate (cite).  Together, this plate-scale observatory would be called NEPTUNE (Northeast Pacific Time Series Underwater Networked Experiments) and would provide continuous observations for 25 years.
By the mid-2000s, NEPTUNE Canada had received full funding and their cabled array was completed and online by 2009.  It was brought under the umbrella network of Ocean Networks Canada (ONC).  Meanwhile, NEPTUNE U.S. was renamed to Regional Scale Nodes and became a component of the OOI.  It is slated for completion in 2014.  Both NEPTUNE Canada and RSN will be integrated through the ONC's digital infrastructure and the OOI Cyberinfrastructure providing real-time access to anyone connected to the Internet.