An amount totalling 95kg of high grade cocaine was allegedly found in suitcases in both cabins, with 29kg in a suitcase in the cabin shared by the two women.
"It is clear there was a large quantity of the substance which appeared to be in safekeeping in the room shared by Ms Lagace and Ms Roberge," Mr Williams told the court.
"It is highly improbable that a person other than the defendant Ms Roberge or Ms Lagace would have stored the items in the suitcase under the bed.
"The cabin space was tiny. The suitcase was reasonably large. All other suitcases in the cabin were emptied.
"It is also clear that Ms Roberge and Ms Lagace shared the cabin for at least 39 days."
Mr Willimas said Ms Roberge and the other two accused of the alleged cocaine plot had booked their tickets for the Sea Princess cruise within a day of each other and used the same travel agency.
He said the two women had shared an email address, both embarked on the ship on July 20, and their emergency contacts for the booking were the same.
He said CCTV footage of the ship's arrival and departures in port showed Ms Roberge and Ms Lagace returning to the ship together. They were with Mr Tamine.
He said the suitcases allegedly found with cocaine were similar in weight and the cocaine within was of a similar level of purity, similarly packaged in ziplock bags and taped with packing tape allegedly found in the women's cabin.
Mr Williams asked Ms Roberge to stand up in court as he asked her three questions as to whether she wanted to give any evidence in relation to the charge against her of importing a commercial quantity of a border-controlled drug.
Weeping loudly, Ms Roberge said "no" three times.
She continued to sob as Mr Williams committed her to stand trial on February 3 for the alleged drug importation.
The two glamorous young women made world headlines after it emerged that they had posted images of the exotic stops on their lavish world cruise on Instagram in the weeks before their dramatic arrest.
Lawyers for Ms Roberge previously argued that the youngest of the three arrested was unaware of the cocaine importation and had spent 40 days sharing Ms Lagace's cabin not knowing what was in the suitcase.
Ms lagace has pleaded guilty to importing a commercial quantity of a border-controlled drug.
Fascinating details of the drug importation, which was Australia's largest by passenger vessel, emerged in Central Local Court last week.
Seven members of the cocaine drug cartel were aboard the Sea Princess as it cruised from New York via Tahiti to Sydney carrying 95kg of cocaine, it was alleged in court.
Crown prosecutor Lincoln Crowley alleged that the two glamorous young Canadian women were an integral part of this "floating warehouse" of drugs, having secreted 29kg of it in a suitcase in their tiny shared cabin.
Along with their co-accused, Andre Tamine, four men who were part of the alleged drug operation were also on board the cruise ship in cabins 706 and 715 as the ship sailed towards Australia, the court heard.
Evidence given during a committal hearing for Ms Roberge alleged that she was a knowing participant in the attempt to import the cocaine into Australia in August this year.
However, lawyer Ragni Mathur argued that Ms Roberge was unaware of the cocaine in her friend Ms Lagace's luggage.
She said Ms Roberge had booked her ticket for the trip with another man who was not associated with the criminal enterprise behind the drug deal.
But Ms Lagace and Mr Tamine had booked their cruise together, Ms Mathur told the court.
Ms Mathur said that Ms Roberge should escape being committed for trial because she was only guilty by her association with Ms Lagace.
On CCTV footage of Ms Roberge embarking and disembarking the Sea Princess she had "nothing in her possession except a wallet or mobile phone".
Whereas Ms Lagace, who carried both an iPhone and BlackBerry - known as a device "that is impossible to decode" - had allegedly told investigators when they asked for it's password "you won't be getting that".
Ms Mathur said that Ms Lagace had admitted an one point that she owned the suitcase in which cocaine was later found.
Crown Prosecutor Lincoln Crowley told the court that although the Crown case against Ms Roberge was circumstantial, she and Ms Lagace had travelled for more than a month in a tiny ship's cabin in which there was a suitcase packed with almost 30kg of cocaine.
"The cocaine, 29kg of it, was found in a cabin occupied by Ms Roberge and Ms Lagace for the past 40 days, packed up, strapped up, taped up and sitting in a suitcase and would be worth a considerable amount of money," Mr Crowley told the court.
"Two women are minding the cocaine. Ms Lagace and Ms Roberge are warehousing a quantity of cocaine.
"It is in effect a floating warehouse. They are sitting on it his until they get to Australia."
Mr Crowley said the almost 30kg of cocaine allegedly found in a Swiss suitcase in the girls' cabin was in layers of Clipseal plastic bags tied up with masking tape.
He said the larger amount of cocaine allegedly found in Mr Tamine's cabin was similarly packaged inside three suitcases.
But Ms Mathur contested that despite the fact that Ms Roberge was a friend of her travelling mate Ms Lagace, that did not mean she knew about the cocaine enterprise.
"You don't need two chickens to keep warm a golden egg," she said.
