Olympic silver medallist Nathan Jon Baggaley and his brother Dru Anthony Baggaley are accused of being involved in a plan to get 650kg of cocaine from a foreign vessel hundreds of kilometres off the NSW coast.

Footage from a surveillance plane from July 2018 was played on Monday as their trial continues in the Brisbane Supreme Court.

Two vessels, one significantly larger than the other, were seen manoeuvring close to each other off Australia's east coast, the jury was told.

Asked if any other observations could be made, surveillance observer Amanda Peace told the court on Monday that "there were some objects in the water in the vicinity of the small vessel".

Dru Baggaley and Anthony Draper - who is expected to testify during the trial - were allegedly on a rigid-hulled inflatable boat (RHIB) that met the larger vessel on July 31, 2018, crown prosecutor Ben Power has told the court.

Black bundles of cocaine, valued at between $100 million and $200 million, were thrown out of the foreign ship during a quick meeting, Mr Power said during his opening.

Footage shown to the court during Mr Power's opening allegedly shows Mr Draper driving the RHIB, while Dru Baggaley throws the "incredibly valuable cargo into the ocean" in the hopes a navy vessel would stop its pursuit, the court was told.

The prosecution alleges Nathan Baggaley also had a "key role" in the importation, saying he bought the RHIB for $100,000, got it ready and covered its registration number in heavy duty black tape before the trip out to sea.

The Crown will also seek to prove Nathan Baggaley communicated or tried to communicate with his brother at sea and drove a boat trailer to Brunswick Heads expecting to meet the cocaine-laden RHIB.

The jury should pay close attention to Mr Draper's evidence, Dru Baggaley's barrister Mark McCarthy said at the start of the trial.

"A key issue, a central focus of the trial of Dru Baggaley, will be whether or not you accept anything at all that Mr Draper tells you," he added.

The prosecution's case against Nathan Baggaley was based on circumstantial evidence that did not prove he was involved in the alleged attempted importation of the cocaine, his barrister Anthony Kimmins told the court.

Dru Baggaley and Nathan Baggaley both pleaded not guilty to a single count of attempting to import a commercial quantity of the border-controlled drug cocaine into Queensland at Coolangatta on the Gold Coast between December 2017 and August 2018.

The jury trial continues.

Australian Associated Press