Navy frigate HMNZS Te Kaha has seized $235 million worth of heroin in a drugs bust on the Indian Ocean.
About $900 million worth of heroin in total was seized in a joint operation with Australian forces also patrolling the area as part of an international campaign against piracy, people-trafficking and drug-smuggling.
The navy said the heroin was bound for Africa and eventually Europe and described the size of the bust as unprecedented.
Commodore John Campbell said the haul was a great outcome for international security and a massive achievement for the Te Kaha crew.
Commodore Campbell said he was not aware of any similar bust in New Zealand's naval history.
He said it was possible the fisherman carrying the drugs in hidden compartments may not have known they were there.
The fisherman were not detained or arrested as the navy does not have the power to do so.
"New Zealand may be a relatively small nation but as good international citizens, we do play our part in maintaining global security," he said.
The navy said the seizure would contribute to international efforts to stem the flow of funds for terrorist activities in the Middle East.
Commodore Campbell was unable to say exactly where the drugs were heading, or where they came from.
"One of the ways that we know that terrorism - or terrorist organisations - are raising money is by shipping drugs, illegal trafficking etc through the region," he said.
"Part of the forensics that we do on the drugs, we take photos - they're wrapped differently, they've got different markings etc on them.
"All of that can be used in a further forensic test later on to determine where they actually come from."
The Naval Criminal Investigative Service (NCIS), which works alongside the navy, said the drugs were between 60 and 80 percent pure.
NCIS special agent Mark Avalos said it was likely the drugs were bound for Africa and eventually Europe but he could not be sure.
"I've collected samples from those seizures. They will be transported to a NCIS agent who will then forward them to the US Drug Enforcement Administration (DEA) for lab analysis and testing at a later date, and that will determine the purity levels and potentially track the origination point for the heroin."
The rest of the heroin was thrown overboard.
HMNZS Te Kaha has begun its voyage back to New Zealand from the Indian Ocean.