Former Australian horse trainer John Nikolic and his wife Yvette were "secretly involved in the wicked, international drugs trade," the High Court in Suva has heard.

Key points: John and Yvette Nikolic sailed from USA to Colombia and were arrested in Fiji in June

John and Yvette Nikolic sailed from USA to Colombia and were arrested in Fiji in June Fiji police found cocaine, other illicit drugs and handguns on the yacht

Fiji police found cocaine, other illicit drugs and handguns on the yacht The Nikolics, from the Gold Coast, pleaded not guilty to five charges including drug possession

The couple, whose voyage on their new luxury yacht, Shenanigans, began in Florida, USA and included a stop in Colombia, were arrested by Fijian border police at Port Denarau on June 22, 2018.

Customs officials found a large quantity of cocaine, 65 tablets of illicit drugs, 2 handguns and 112 rounds of live ammunition on the yacht, the court heard.

The Nikolics pleaded not guilty to five charges, including four related to the importation and possession of illicit substances, as their trial in Fiji started on Monday.

In his opening statement, lead prosecutor Lee Burney said the name of the Nikolics' yacht may have been a joke.

"Perhaps this was an in joke between her and her husband," Mr Burney told the court.

Lead prosecutor Lee Burney said the Nikolics hid their crimes by appearing to be "living the dream". ( ABC: Lice Movono )

"Because to the outside world they were living the dream, embarking on an adventure of a lifetime.

"Whereas in reality they were secretly involved in the wicked, international drugs trade."

"Mr and Mrs Nikolic made no secret of their epic voyage from Florida, the US, stopping off in Colombia, through the Panama Canal and visiting several beautiful islands on their long journey across the south Pacific, headed for their home base on the Gold Coast of Australia."

Mr Burney said Mr Nikolic filed an electronic declaration as required under Fijian law, but the yacht was still searched by Fijian Customs officials.

"You may think there was a flawed genius of Mr Nikolic to hide in plain sight, but the reality of the modern world is that it is extremely difficult to conceal the movements of a super yacht.

"As things turn out there was no hiding," he said.

The Nikolics have been in custody since their arrest.

With 17 witnesses due to take the stand, Mr Burney said the trial could take longer than the week it has been scheduled for.

Search uncovered drugs, guns and cash

The court heard it was after authorities discovered a blue bag containing 10 blocks of cocaine in a locker under the front deck of the yacht, Mr Nikolic attempted to take his own life.

"It is the prosecution's case that upon being confronted with the 10 bars of cocaine and realising that his shenanigans had been exposed, Mr Nikolic indicated to the officers where they would find a further three bars of cocaine and he accepted sole responsibility for the drugs," Mr Burney said.

"After the discovery of the drugs, Mr Nikolic asked to speak with his wife and in a dramatic turn of events, after first visiting the washroom, Mr Nikolic collapsed beside his wife, after a brief conversation with her.

"Now at that point the focus of the officers quite properly shifted, to Mr Nikolic's wellbeing. Clearly he was in a bad way. A doctor was called."

The court heard the doctor arrived to find Mr Nikolic in the recovery position, and concluded he was in respiratory arrest following a drug overdose.

He was taken to hospital and remained there "gravely ill" for several days.

"Following the drama of the attempted suicide a thorough search was resumed and the officers found, concealed behind a panel in the lounge area, 65 tablets, two handguns and (112) rounds of live ammunition and 15,000 US dollars," Mr Burney said.

"It is clear beyond a shadow of a doubt that Mr Nikolic had knowingly bought drugs and ammunition into Fiji unlawfully."

The court heard that Mrs Nikolic was also accused in this case because she was the owner of the yacht, he was the skipper and they had lived aboard the vessel for several months.

"It is the prosecution case it was Mr Nikolic's parting gift to his wife to attempt to provide her with the life raft of a false defence," Mr Burney said.

The trial continues.

Editor's note: A previous version of this story stated that the Fijian police had searched the yacht. The story has been updated to clarify that it was Customs officials who conducted the initial raid before police later made the arrests.