NEPTUNE differs from a conventional submarine telecommunications system in two key respects. First, NEPTUNE requires data input and output at many seafloor sites rather than a few land terminuses. Second, NEPTUNE has to distribute power at variable and fluctuating rates to many seafloor instruments in addition to energizing its own internal systems. For these and other reasons, the engineering solution for the NEPTUNE power and communications systems does not closely resemble those used in commercial telecommunications systems. However, NEPTUNE will take advantage of the submarine fiber optic cable technology used in telecommunications for its backbone, and will be installed using conventional cable laying assets.