This dataset contains activity data from thirteen common guillemots (Uria aalge) from the Isle of May during the 2005-2006 annual cycle. These biologging data were collected using global location sensing (GLS) time depth recorder (TDR) devices. From these data we derived daily data on guillemot activity budgets, sea surface temperature values, energy expenditure, location fixes and the proportion of dive activity that occurred during day, twilight and night. Data on colony attendance were also collected using daily time-lapse photography.