Melina Roberge, 23, and Isabelle Lagacé, 28 -- as well as a third Canadian, 63-year-old Andre Tamine, who could also face a life sentence -- were refused bail this week, a source close to the case told CNN.
The three have been charged with importing drugs of a commercial volume into the country, Australian Federal Police said in a statement.
The haul reportedly has a street value of around AUD$30 million ($23 million), and police told CNN affiliate Channel 7 that the seizure was Australia's biggest-ever drug bust through a "passenger stream."
The roles of the three arrested were yet to be determined, police said, and further arrests have not been ruled out.
Coconuts, bikinis and tattoos
The police statement said that Australian Border Force officers boarded the vessel over the weekend when it berthed in Sydney Harbour. Authorities used sniffer dogs to search a number of passenger cabins on the ship. Around 95 kilograms of cocaine was found packed in suitcases, it said. On Facebook, the agency joked that the three "did not have much room for clean underwear or spare toothbrushes."
The two women involved appear to have documented much of their trip on Instagram, two photos showing them drinking from coconuts while kneeling in the water at a Tahiti beach in bikinis.
Others show them driving dune buggies in Peru, while another appears to show Roberge getting a leg tattoo in Tahiti. Lagacé is pictured on her own account wearing a necklace made from beads in the shape of marijuana leaves.
Where the women boarded the ship was not immediately clear, but the most recent Instagram pictures were posted on Thursday last week from Tahiti, three days before the drug bust.
The women appear to have also traveled to Bermuda, Chile, Ecuador and Colombia, the posts show.
The photos have attracted a flurry of negative responses on Instagram.
The drug bust involved collaboration between several Australian police agencies, as well as security, customs and border services in Canada, the United States and New Zealand.
The source who spoke to CNN said that the three nationals were currently detained in Sydney and explained that trials on the trafficking of commercial amounts of drugs typically take 12 to 18 months.
CNN was not able to immediately contact the Canadian nationals or their lawyer.