A number of anthropogenic activities that occur in coastal and offshore waters generate sound or impulses at levels which are sufficiently high to pose a risk of causing physical damage or hearing impairment in sensitive wildlife such as marine mammals. The use of explosives, for example, for well-head removal, certainly poses this risk and it is possible that pile driving during windfarm construction could also do so. One potential means of reducing the risk of damage to marine mammals from such activities is to move sensitive animals out of the high risk area by using aversive or alarming sounds produced by an acoustic mitigation device (AMD). This report investigates the potential for using AMDs for mitigation during windfarm construction, explores the types of acoustic signals that might be suitable for this application, and the devices available for producing them in the field. It makes recommendations in relation to the areas of research that would be needed to develop and quantify the performance of a working system, and reviews legal aspects of using AMDs for mitigation in UK waters.