Gardaí are still questioning five men about an alleged effort to bring drugs reportedly worth up to €100 million into the country.
It is believed they were transferred from a large vessel to a smaller boat off the Kerry coast on Monday.
Gardaí suspect the drugs were being routed through this country from South America to be transported into mainland Europe and are no longer in the Irish jurisdiction.
They think a gang moved a substantial amount of drugs off a large vessel to a smaller boat, at a stretch of water off the Kerry coast, early last Monday morning.
They do not believe the larger vessel was aware of the movement of the drugs and continued on a scheduled sailing path.
Four of the men, who are aged 30, 31, 39 and 45, were arrested by Gardai at Meenogahane, Co Kerry in the early hours of last Monday and are being held at Garda stations in the county.
The fifth man, a 28-year-old was detained on board a cargo ship sailing on the Shannon Estuary on Wednesday and he's being held at a garda station in Co. Clare.
A number of boats were searched but it is understood no drugs were found.
Main image: Gardaí. Image: Leah Farrell/© RollingNews.ie