For Andre Tamine, Melina Roberge and Isabelle Lagace, it seemed to be the trip of a lifetime.

The Canadian trio had criss-crossed the globe on a seven-week Sea Princess cruise, boarding at Southampton in England and making stops including Ireland, the US, Canada, New Zealand and South America.

But when the ship sailed into Sydney Harbour on August 28, 2016, the holiday came to an abrupt end when the three were arrested.

Melina Roberge and Isabelle Lagace.

They had been identified as "high-risk" passengers on a "high-risk" ship, which was closely scrutinised by authorities because it had stopped at a large number of ports.