Customs Officers have seized around 75kg of cocaine with an estimated street value of over €5m.
The drugs were found after a tip-off from the public through the “Customs Drugs Watch Programme”.
Revenue Officers from the South West region uncovered a suspicious item on the shore near Liscannor, Co. Clare.
The "torpedo type" device held the cocaine, which Revenue say may have been attached to the hull of a ship below its waterline.
However, Revenue cannot say where the drugs came from, or where they were being sent.
Investigations are continuing.
They have the public not to put themselves in danger by approaching or interfering with suspicious items such as this.
Instead, Revenue are encouraging people to report unusual or suspicious activities to Revenue Customs Service on their Freephone number at 1800 295295.