The drugs were uncovered in a truck from Holyhead
A man has been arrested after Revenue officers seized cannabis worth an estimated €2.4m.
It was part of an intelligence-led operation at Dublin Port on Wednesday night.
Officers - assisted by the Garda National Drugs, Organised Crime Bureau and the Special Crime Task Force - seized 376kg of cannabis resin and 9.7kg of herbal cannabis.
The illegal drugs were uncovered in crates in a truck that had disembarked the evening ferry arriving from Holyhead.
It followed a positive indication on the truck by drugs dog Holly, and the van was then subject to Revenue's mobile x-ray scanner.
A 41-year-old Northern Irish man was arrested and is being held at Store Street garda station.
Revenue say investigations are ongoing with the cooperation of the Police Service of Northern Ireland (PSNI).