A garda spokesperson said: “A man was arrested in connection with the investigation and is currently detained under Section 4 of the Criminal Justice Act, 1984 at a Garda Station in the eastern region.”.
The incident occurred on a 2pm Stena Nordica sailing from Fishguard in Wales to Rosslare Europort, and the ferry docked in Co Wexford.
A Stena Line spokesperson said: “As this is a live police matter, we cannot provide any further detail on the incident at this time.”.
A number of Stena Nordica services were cancelled to assist with the garda investigation.
A man continues to be questioned by gardai following the death of a woman on board a passenger ferry.
