Various and detailed work are required on the construction work site. Because most the work are actions on natural objects under native environments, and even the states of artifacts are change as the progress of work. Construction work are great different from factory work which are easy to set up the working conditions and easy to standardize. Therefore above-mentioned is contributes to human-intensive construction work. Especially, even mechanizations of coastal work which are underwater work for coast and port improvement still are limited and are diver-intensive because these work are constrained by underwater visibility, crowded structures, disturbances like wave and current, and so on. However, extended underwater operations put a great physical strain on divers, and the work conditions are severer than that on land in many circumstances. And, they are difficult to detect and to avoid the danger of accident because of numerous ships come-and-go in port area. Therefore, unmanned underwater work should be considered fundamental solution for above-mentioned various problems because the underwater accidents become life-threatening serious situations in most cases.
　In this paper, present situation of the coastal work will be described. And, proposed unmanned approaches for two cases of the enumerated underwater work are “shore line survey in erosive coast” and “maintenance examination for mooring facility of massive floating structure”, which will be described. Purposes of this study are not only realization of the unmanned approaches but also contribution to future similar approaches through provisions of the process sequences under certain conditions with specific cases. In this study, approaches for unmanned underwater operating systems are not limited to automated technologies. Tele-operation technology utilizing superior great human abilities which considered the characteristic conditions is treated as valuable fundamental technology.
　In addition, this paper is the author’s republished doctoral dissertation which is formatted to fit the technical note of the port and airport research institute.