One travelled from a faraway continent hoping to pay off debts belonging to his girlfriend's dad.

Another was promised $50,000 to help deliver what turned out to be an estimated quarter-billion dollar meth haul.

Now, The-Hoang Thai and Isaiah John Te Hira will spend years behind bars for their roles in the 2019 international drug conspiracy.

The High Court in Auckland today heard the methamphetamine was stashed inside 60 electric motors sent from Thailand in a shipping container.

The 469kg shipment Customs and police found in the electric motors exceeded even the infamous 449kg stash discovered at Ninety Mile Beach five years ago.

Thai, a Canadian national, pleaded guilty to two charges of meth possession for supply.

Auckland man Te Hira admitted one charge of importing meth and one of possessing the Class A drug for supply.

"Once upon a time this would have been the most unusual importation," Te Hira's defence counsel Maria Pecotic said.

"The imports into New Zealand now are getting larger and larger."

She said Te Hira had been expecting the drugs to arrive in ovens, not motors.

"He'd only organised one storage place. There were many discussions about where they were going to put the rest of it. It wasn't very organised," Pecotic said.

"Clearly, that shows his lack of knowledge."

She said her client was now working hard to undo damage incurred during his dysfunctional and turbulent childhood and upbringing.

The court heard intercepted communications showed a person known as "Lucky" sent instructions to Thai.

Thai's defence counsel Julie-Anne Kincade QC said her client passed those instructions to others.

Kincade said Thai, 25, was less influential in the drug syndicate than the Crown alleged.

"It is those that are at the forefront of the communications who are often lower down the ladder."

Thai grew up in Toronto and was a supportive big brother who looked after younger siblings but had no good adult role models when growing up, Kincade said.

His mother abandoned the Vietnamese-Canadian family when Thai was 12, the court heard.

Prosecutor Henry Steele challenged suggestions the two men weren't aware of the scale of the meth importation.

"They clearly know whatever's coming is large."

Steele said Thai's second charge related to a separate 26kg pile of meth which he gained "by hook or by crook".

Thai and Te Hira were caught after Customs launched an investigation into suspected drug importation through a company called NZ Importing Group Ltd.

Justice Kit Toogood said a local logistics company unwittingly became involved.

Customs found the drugs in August 2019 after searching the shipping container which arrived from Bangkok.

Customs arranged for a controlled delivery to Mangatawhiri in the north Waikato. Some meth was removed and replaced with placebos.

Police later joined Customs on massive raids across Auckland and its outskirts before the haul was revealed to the public.

Justice Toogood said Thai came to New Zealand solely to be in the drug trade, and to pay off gambling debts his girlfriend's father had amassed.

Thai had no friends in New Zealand, only criminal associates, and the girlfriend and her dad now seemed to have abandoned him, the judge added.

The judge called the vast meth stash "a virtual mountain of misery".

The court was told Te Hira had expected $50,000 for helping offload the drugs, and Thai had given him instructions.

Te Hira made a "terrible mistake" chasing what he thought would be easy money, Justice Toogood said.

Both men kept their heads down in the dock as the judge sentenced them.

Thai was sentenced to 20 years and 6 months' imprisonment

Te Hira was sentenced to 16 years' imprisonment.