Cocaine with an estimated value of around £4million has been seized at Avonmouth docks.
As part of an investigation involving the National Crime Agency (NCA), officers searched a vessel on Tuesday 9 November.
The boat, which was carrying a load of fruit juice, had previously sailed from Santos in Brazil, and was due to continue on to the Netherlands.
Around 46 kilos of cocaine was recovered from what investigators believe was a specially adapted hide attached to the hull of the vessel.
If cut and sold in the UK, the haul would have had an estimated street value in excess of £4million.
An international investigation into the source and intended destination for the drugs is now underway, involving the NCA and partners in Brazil and the Netherlands.
NCA Branch Operations Manager Dean Wallbank said: “Disrupting the international networks involved in drug trafficking is a priority for the NCA, and I’m grateful for the assistance provided by partners in Border Force and Avon & Somerset Police on this operation, as well as those overseas.
“While we don’t believe the entire load was destined for the UK initially, it is likely that at least some of it would have ended up back here in the hands of UK criminal gangs, being sold on UK streets.
“Making this seizure has prevented them from profiting further and re-investing in further criminality.”
The investigation included officers from the Border Force National Deep Rummage Team, specialist NCA search officers, and divers from Avon & Somerset Police.
Inspector Will Barlow from Avon and Somerset Police said: "We are pleased that our experienced dive team were able to play a significant role in recovering a large quantity of class A drugs.
"The officers involved reported facing extremely challenging conditions during this operation, in particular very poor visibility.
"We are all acutely aware of the damage cocaine and other illegal substances can have on our communities and we are delighted to have been able to support the National Crime Agency and Border Force with their investigation and stop harmful drugs from making their way on to our street."