The cash was found in the boot of a car about to be driven onto the Commodore Clipper to Portsmouth last weekend during a search of outbound vehicles.
The cash was seized under the Drug Trafficking Offences Law and two passengers were arrested – a man and a woman who are both Island residents.
They were interviewed by officials and then released pending further investigations.
Mark Cockerham, the manager of anti-smuggling and investigation for Customs, said: ‘Seizing cash that we believe is the proceeds of drug trafficking at the frontiers is essential.
It is an effective deterrent against the organisation of the importation of large commercial quantities of drugs into the Island.’