The National Crime Agency (NCA) said officers seized more than half a tonne of the Class A drug on a boat travelling from Colombia, at London Gateway on the Essex coast, south-east England.
Investigators intercepted the shipment, which had been en route to the Netherlands, on Tuesday.
Hundreds of huge cocaine slabs were found wedged alongside bananas in cardboard boxes.
The NCA said the haul would have had a UK street value of more than £40 million once cut and sold.
NCA branch operations manager, Adam Berry, described the discovery as a “huge blow” to the peddlers.
He said: “Taking out a consignment of this size will have been a huge blow to the criminal network involved in this shipment, preventing them from making millions of pounds that would have been invested in further criminality.
“Class A drugs are pedalled by gangs involved in violence and exploitation in our communities.
“The NCA works hard with partners to stop drugs getting that far, and making seizures like this demonstrate how we can break that link between international drug cartels and street-level dealers.”
