While out on exercise today at Ireland's Eye, Howth Coast Guard boat was tasked to a report of a person in a lifejacket swimming offshore near the Martello tower in Portmarnock. The boat proceeded to the area and found a swimmer with a brightly coloured buoy attached to them. The swimmer was using it as a visual aid so they could be seen while swimming. No assistance required. Considered call with good intent. Howth boat returned to exercise.