An instrument at the ocean bottom connected to the land by a cable that provides power for the measurement and transmission of data from the seafloor to the coast. Cables can extend for tens of kilometres offshore and across oceans. They enable real-time, multi-sensor seafloor observatories to be deployed for long-term monitoring. Examples of sensors on cabled systems are seismometers to measure earthquakes, sensitive pressure gauges to measure tsunamis, geodetic sensors to measure seafloor deformation, and cameras. Japan operates several cable systems.