New Zealand police, customs and defence officials united for Operation Hydros to secure the haul, recovering 81 bales of the illicit drug totalling 3.24 tonnes.
Police Commissioner Andrew Coster said it was "one of the single biggest seizures of illegal drugs by authorities in this country" and worth an estimated $NZ500 million ($A453 million).
"This is the largest find of illicit drugs by New Zealand agencies by some margin," he said.
"We believe there was enough cocaine to service the Australian market for about one year and this would be more than New Zealand would use in 30 years."
The cocaine was found in international waters northeast of New Zealand not long after it was deposited.
Detective Superintendent Greg Williams said the strategy of the drug traffickers - to leave packaged drugs in international waters for other vessels - was widely employed.
"Cocaine floats," he said.
"It's basically set up into nets ... with flotation devices and the aim is for them to sit there and at some point, someone is going to come and get it.
"It's not uncommon. In recent times for instance, cocaine has washed up in Tonga."
Police declined to comment on how the cocaine dump came to their attention.
Mr Williams said the cocaine might have been headed to New Zealand in transit but there was no doubt in his mind the final destination for the drug was Australia.
"New Zealand is not a cocaine market in essence," he said.
"We consume at the moment about 1.7 kilos a week and that's increased dramatically in the last half a year.
"The prices are high here compared to the US - that's why they bring it here -but we are tiny compared to Australia.
"There is no way 3.24 tonnes is coming here. Australia is the market."
The cocaine has been brought back to Auckland after a six-day journey on board the HMNZS Manawanui and will be destroyed.
Mr Coster said the sheer scale of the discovery meant it would severely disrupt an international drug trafficking syndicate.
"There is no doubt this discovery lands a major financial blow right from the South American producers through to the distributors of this product," he said.
"The distribution of any illicit drug causes a great amount of social harm as well as negative health and financial implications for communities, especially drug users and their families."
No arrests have been made.
New Zealand Defence Force Joint Forces commander Rear Admiral Jim Gilmour said defence was happy to play its part.
"We had the right people and the right capabilities to provide the support required and it was great to work alongside the New Zealand Police and the New Zealand Customs Service," he said.
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