Gardai have seized cocaine with an estimated street value of up to €35 million - potentially as much as half a tonne of the drug.
The drugs were disguised in bags of coal and smuggled in two large containers from South America to Rotterdam.
Forensic Science Ireland is still examining the coal bags to determine the total amount of cocaine seized, but it's estimated to weigh up to half a tonne.
In a statement, the force explained: "GNDOCB believe an attempt was being made by an organised crime group to import up to half a tonne of cocaine into Ireland
"In the course of the investigation and following ongoing liaison with relevant law enforcement authorities in The Netherlands, An Garda Síochána took possession of two shipping containers that arrived a number of weeks ago, at Rotterdam Port.
"An Garda Síochána has received assistance from the Irish Navy and Customs & Revenue in arranging for the transportation of the relevant two containers to Ireland. The containers subsequently arrived at Dublin Port and were brought ashore under armed escort."
Forensic teams are continuing to examine the drugs, while gardaí say they expect to arrest a number of suspects in the near future.
Assistant Commissioner John O’Driscoll called it a "significant development" in efforts to disrupt and dismantle organised crime gangs.
He added that the operation had a "significant international dimension".