The rapid increase in marine renewable energy installations (MREIs) will result in the placing of many novel man-made structures within seabird foraging habitats, and such structures could potentially impact seabird populations directly and indirectly, positively and negatively. However, whether these potential impacts represent real ones, such that they cause detectable trends in population levels, remains unknown. Changes in population dynamics of seabirds are driven primarily by rates of reproduction and adult and juvenile survival, all three of which are impacted by foraging success. Therefore, revealing precisely how MREIs can affect seabird foraging success through changes in foraging behaviour is key to understanding whether large-scale installations could have impacts at a population level. Discussion focuses on how to define foraging habitat and how MREIs might impact those habitats and foraging behaviour indirectly by changes in oceanographic processes and prey characteristics. Foraging behaviours are also likely to be more directly impacted by MREIs, so focus here is also on how changes in foraging behaviour during the more constrained breeding season can influence reproductive output by altering individual energy budgets. A third and more-direct potential impact of MREIs on foraging behaviour is changes in diving behaviour. Throughout, relevant gaps in current knowledge that need to be addressed in order to make robust predictions as to how MREIs might impact seabird populations are highlighted.