The wave energy industry is progressing towards an advanced stage of development, with consideration being given to the selection of suitable sites for the first commercial installations. An informed, and accurate, characterisation of the wave energy resource is an essential aspect of this process. Ireland is exposed to an energetic wave climate, however many features of this resource are not well understood. This paper utilizes metocean datasets that have previously been unavailable for exposed Irish sites to investigate some interesting characterises the wave energy resource at the Atlantic Marine Energy Test Site (AMETS), a facility for conducting sea trials of floating wave energy converters that is being developed near Belmullet, on the west coast of Ireland. Previous work by the authors has provided summaries of the wave climate at the site and how is varies over seasonal and interannual timeframes. Here a number of commonly made assumptions in the calculation of wave power are contested, and the uncertainties resulting from their application are demonstrated. The relationship between commonly used wave period parameters is studied, and its importance in the calculation of wave power quantified. Additionally, observations of the extreme wave conditions that have occurred at the site and estimates of future storms that devices will need to withstand are presented. The implications of these results for the design and operation of wave energy converters are discussed. The foremost contribution of this paper is the development of an enhanced understanding of the fundamental nature of the wave energy resource at the Atlantic Marine Energy Test Site. The results presented here also have a wider relevance, and can be considered typical of other, similarly exposed, locations on Ireland’s west coast.