The chief officer of a global livestock transportation vessel is among four individuals charged with attempting to smuggle more than half a tonne of cocaine, discovered adrift off Western Australia’s coast.

The significant find occurred on November 6 after members of the public stumbled upon packages affixed to flotation devices approximately 30 kilometers from shore.

Authorities eventually retrieved the bundles from the waters near Lancelin, located about 125 kilometers north of Perth.

The seized haul amounted to 525 kilograms of cocaine, with an estimated street value exceeding $170 million.

Authorities allege the drugs were jettisoned by an international livestock carrier en route to Fremantle Harbour.

A day later, a 46-year-old Croatian man, who was the chief officer of the vessel, was arrested.

A blue drum and ropes similar to those found with the drugs were found in a search of the ship, whilst police also allege a CCTV camera had been blocked whilst the drugs were being offloaded.

Three other men were also charged in relation to the attempted importation, with two men being tracked down by authorities after getting into distress in the open water.

On November 3, emergency services were called to a boat that was taking on water off the coast of Guilderton.

Two men from Sydney, aged 19 and 36, were found and brought safely to shore, whilst further investigations led to the identification of a 52-year-old Perth man.

It is alleged the trio made multiple attempts to retrieve the cocaine from the ocean after launching boats from the Two Rocks Boat ramp.

They were all subsequently arrested, with the two Sydney men being extradited to Western Australia.

The four men have been charged with multiple offences, with the 19-year-old man and the 46-year-old Croatian man facing the most severe penalties of life imprisonment if found guilty.

Police say investigations are ongoing, including into the origins of the cocaine, and they believe more arrests will be made.