Offshore construction developments may lead to the generation of man-made underwater noise as a by-product of the activities followed and this has the potential to impact on marine life. Marine renewables projects, although often cited as “environmentally friendly” are no different in this regard. As part of the consenting process, the regulatory authorities require that such projects undergo a programme of assessment in order to determine the scale and significance of any environmental impact that may occur. Aquamarine Power Ltd is involved in the development of a site off the west coast of the Isle of Lewis, Outer Hebrides for the installation of a number of their Oyster 800 wave energy converters. During the consenting requirement and as part of the baselining process prior to any development taking place, seagoing surveys were undertaken. The surveys indicated that a number of species of marine mammals, including harbour seal, common dolphin, harbour porpoise and minke whale were often found in and around the project area. It is noted that these are all classified as European Protected Species and are thus legally protected from harassment including that which may arise from man-made underwater noise. Such animals make use of sound to hunt and to communicate and are thus sensitive to disturbance when this capability becomes compromised. The construction process is likely to involve the drilling of sockets in the seabed in which foundation piles are located while the installation process will require the use of specialist vessels equipped with lifting gear and dredging units in order to prepare the seabed in the project area. In the absence of more relevant data, the operational characteristics of the wave energy devices were based on data extrapolated from other underwater devices of similar power output. This paper outlines the procedures followed by Kongsberg Maritime Ltd when they were tasked to produce an acoustic impact assessment on behalf of the developer. It describes the tasks and equipment used in terms of their likely acoustic source levels and frequency spectra. The paper goes on to show how through the modelling of underwater sound and the application of acoustic impact models, the potential impacts on environmentally sensitive sites close to the wave energy development were quantified. The ensuing analysis indicated that the acoustic impacts likely to occur from the installation and operation of the wave energy development were deemed to be relatively insignificant. As a result, the project received full consent from the Scottish Government in 2013.