James Lake-Kusviandy Blee, 24, plotted with his father James Lake Blee and two Brazilian divers to obtain a 57kg package of cocaine on May 9, 2022.
The drugs were concealed within the hull of the Arti Gr Majura which had transported soy bean meal from Argentina to the Port of Newcastle.
Only one of the divers, Jhoni Fernandes Da Silva, returned to the surface and police found the body of his compatriot Bruno Borges Martins floating in Newcastle Harbour.
Da Silva fled and has never been apprehended by police.
Blee Jr was found guilty on Wednesday of attempting to possess a commercial quantity of an unlawfully imported border controlled drug by jurors at Sydney's Downing Centre District Court.
His bail was immediately revoked.
A package containing 42 individual packets of cocaine was wrapped in black tarp and found by water police washed up on nearby Kooragang Island.
NSW Police examining the packages found it contained almost 35kg in pure cocaine.
The divers were equipped with a variety of gear, including rebreathers and seabobs, to dive down 10 metres and obtain the drugs from a compartment on the cargo ship known as the sea chest, the jury heard.
Blee Jr denied knowing about the plot, telling the court that he thought he was running errands for his father.
He travelled by yacht from Darwin to Bali in Indonesia in February 2022.
Blee Sr then travelled to Dubai where he met a man known as Irish to get details about the drug plot.
In April 2022, the father and son left Bali on a yacht bound for Darwin with the two divers.
After Martins failed to return from the dive operation in the harbour, Blee Jr bought a one-way plane ticket back to his home in the Gold Coast.
He will be sentenced on July 24.
In November 2024, James Blake Blee was sentenced to 11 years and three months' imprisonment for the offences, with parole eligibility after seven years and six months.
He pleaded guilty to importing the border-controlled drug and smuggling the two Brazilians into the country.
Blee Sr agreed to the plot in a gamble driven by financial stress after his business collapsed during the COVID-19 pandemic, the court heard in 2024.
He will be eligible for parole in November 2029.
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