The potential for sea-wave-energy exploitation is high in waters around the UK. Generating stations would typically be 2000 MW in rating, about 30 km long and be situated 10—15 km offshore, the energy being transmitted as electricity in submarine power cables. For such developments to be economic, a high degree of plant availability is necessary so that the maximum amount of energy can be converted and transmitted ashore. This requirement for high availability leads to the need for carefully designed protection and monitoring equipment. In addition, because the plant will be unmanned and because maintenance can be carried out only during short periods of the year, control, operating and monitoring philosophies must be developed, which may be quite different to those normally applied on land-based systems. In the paper, an approach is described which bases control, operating and maintenance around comprehensive condition monitoring of generating plant. Details are given of how information from such instrumentation can be used not only for health monitoring of plant, but also as an aid to operation and to scheduling and design of maintenance procedures.