The ship arrived at the Port of Melbourne from South America on October 7, with a suspicious attachment identified on its hull below the waterline.
Specialist divers retrieved four packages of cocaine with a combined weight of 154kg wrapped in plastic from inside the vessel's sea chest.
It's estimated the massive haul equates to about 77,0000 street deals.
Australian Federal Police officers seized the drugs and a suspected tracking device, launching an investigation to identify the cocaine's source and its intended destination.
General crew on the ship can't access the area.
It is the second attempted import of its kind in two months after 200kg of cocaine was seized from the sea chest of another vessel docked in the Port of Melbourne in August.
AFP Assistant Commissioner Hilda Sirec said the smuggling tactic was a rising trend for transnational organised crime groups.
"My message to organised crime is that your modus operandi is busted," she said in a statement on Tuesday.
"We know when illicit drugs are coming in and where they are stored."
She also warned divers against retrieving the illicit drugs.
"They are also placing themselves in serious danger because retrieval often involves diving through dark, busy shipping channels with limited safety equipment," she said.
"It's just not worth risking your life or your future for."
Australian Border Force Commander Clint Sims said cocaine shipments were being seized at Australia's borders at record levels,
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