Police have seized more than 800 kilograms of cocaine that was destined for Western Australia, describing it as one of the largest hauls of the drug in decades.
Details of the joint agency investigation were revealed today, which began with a tip off about an alleged plot to drop the massive cache of drugs - with a street value of about $320 million - into the ocean for collection sometime in May.
The international drug syndicate's plan began to fall apart when three men, who allegedly set out on a cabin cruiser to retrieve the drugs, ran into engine trouble off Rottnest Island on May 24.
Following an investigation into bulk cargo vessels in the area at the time, police boarded the merchant vessel ST Pinot, which had travelled to WA from South America.
After being moved to a berth in Kwinana, navy divers found 29 packages containing one kilogram blocks of cocaine on board, which had been submerged in a water-filled ballast tank.
AFP Assistant Commissioner Pryce Scanlan said the detection and arrests came about through co-operation between multiple agencies.
"The Australian Federal Police, Australian Border Force, West Australian Police Force, Australian Criminal Intelligence Commission and the Department of Home Affairs have combined all of our resources to stop this attempt by organised crime to profit at the expense of our communities," he said.
"The navy clearance divers spent more than 90 minutes on board this vessel in a confined space to extract this quantity of drugs from the flooded ballast tank.
"The interception of this amount of drugs would be a significant blow to well resourced syndicates and prevents millions of dollars of drug profits flowing back to the criminals involved in this drug venture."
Assistant Commissioner Scanlan said there was already an operation focusing on bulk cargo carriers headed for WA ports when the circumstances surrounding the three men aboard the cabin cruiser aroused suspicions.
The vessel, named No Fixed Address, was purchased with cash soon before it allegedly headed out to retrieve the drugs, before the men had to be rescued due to "engine trouble".
"Our suspicions were heightened somewhat after this vessel started heading out towards that particular vessel and became in distress," the assistant commissioner said.
"There was no transfer of any drugs.
"You've got three novices on a boat that have no idea what they're doing going out to collect drugs, get into distress and it just heightens our suspicions.
"Someone walking in with an amount of cash to pay for a boat and immediately going out towards a shipping vessel is pretty suspicious."
The three men men, aged 21, 25 and 29, have been charged with attempting to import a commercial quantity of a border-controlled drug.
Two of the men are Perth residents and the other, a Lithuanian national, was arrested in Sydney as he was trying to leave the country.
Assistant Commissioner Scanlan said investigations were continuing, and the ship was still being searched and seized devices were being examined.
He said Australians paid high prices for drugs, which made the country attractive to cartels.