A request from the MV Oriana via the Irish Coastguard's MRCC Dublin (Marine Rescue Co-Ordination Centre) was made for the man who had taken ill around mid-night and was being treated by a ship's doctor.
Dun Laoghaire's All-weather lifeboat was tasked under Cox'n Ken Robertson with a volunteer crew including Dr. Sarah Brookes and launched at 4.20am to meet the 6,000-tonne cruise ship on Dublin Bay.
Dun Laoghaire's lifeboat station is online, with regular updates coming from their Facebook Page.