The Royal Navy has seized 5.5 tonnes of cocaine, with an estimated street value of £240 million.
The seizure was made by HMS Iron Duke from a 138ft fishing boat off the coast of South America.
The shipment comprised 212 bales of cocaine, weighing about 26kg each. The drugs were found hidden beneath the ship's regular stores.
The BBC reports the seizure is the third for HMS Iron Duke off South America in recent months.
In July and August, the ship was involved in two operations when cocaine with an estimated street value totalling £39 million, was seized.