A widely accepted definition of seafloor observatories has been described as an unmanned system of instruments, sensors and command modules connected either acoustically or via seafloor junction box to a surface buoy or a cable to land. These observatories will have power and communication capabilities (Favali & Beranzoli, 1996). Accordingly, a seafloor observatory is characterised by a data acquisition and control system, multiple sensors, long-term autonomy, communication systems, remote re-configuration of mission parameters and accurate positioning. The sensors themselves are suitable for long-term operation, when properly installed to provide highly reliable data.
There are many indications that these experimental projects will be the forerunners for a technology that will become widely used for marine monitoring activities in the future, covering multi-disciplinary topics such as climate change, seasonal changes, interchange monitoring, earthquake and deformation studies, deep sea ecology, water column processes, fisheries and marine mammals research.