Fawzi Salem Ukili Al Majed was testifying at the trial of Maythem Kamil Radhi who has denied facilitating the proposed entry of at least five non-citizens into Australia in 2001.
The Brisbane Supreme Court jury has been told the events of the case involve a voyage that left Indonesia and sank at sea leading to a "significant number of lives being lost".
The Iraqi-born Radhi was not the kingpin of the group that tried to bring the non-citizens into Australia, but instead one of those who helped the leader Abu Quessy, prosecutor Chris Shanahan told the court in his opening address.
Radhi, 46, is accused of doing one or more things like collecting money, arranging buses, visiting places where passengers stayed before the journey and helping organise people at the vessel's departure point on the beach.
The Crown alleges this occurred between July 1 and October 19, 2001.
Mr Shanahan said jurors would hear evidence about the boat - referred to as the Suspected Illegal Entry Vessel (SIEV) designated X - sinking on the way to Australia.
Some 20 passengers who became concerned about the seaworthiness of the boat disembarked and returned to Indonesia before it sank, while others were rescued, he added.
Mr Al Majed told the court on Monday he paid $US700 per person for himself, his wife and three children to travel to Australia after negotiating a reduced rate.
He said he had communicated in Arabic to "Maythem" and other men about arrangements to travel to Australia to "be in a safe country" while in Indonesia for three to four months.
At one place where they stayed only women could sleep inside, they were not allowed to leave the accommodation's precincts and their only food was bread and cucumbers, he said.
Mr Al Majed said men armed with guns were present when they got onto a smaller boat that took them out to the SIEV-X during the night.
He estimated there were between 500 and 520 people crowded on the SIEV-X and once out at sea the waves were up to 10 metres.
Mr Al Majed said that when they entered international waters the Indonesian captain was taken back to shore and an Iraqi who had never captained a boat of that size was put in charge.
After about 15 hours at sea, the SIEV-X came across a fishing boat that had been been lost for days and run out of food, he told the court.
After giving the fishermen food, Mr Al Majed took his family and another 21 people back to Indonesia on that boat.
Another five surviving passengers are also expected to testify during the trial.
They were not Australian citizens and did not hold valid visas to enter the country.
Defence barrister Mark McCarthy said prosecutors needed to prove Radhi's alleged involvement was over several months from July 1, 2001.
He told jurors to ask themselves during deliberations whether evidence showed that what Radhi did was done with the intention to facilitate the proposed entry into Australia of the group of at least five people, while reminding them the events occurred more than two decades ago.
"I ask you to keep in mind the need to assess the extent to which the recollections of witnesses that they share with you in this court may be affected by the passage of time," he added.
"The issue in this trial is what did he (Radhi) do, what did he intend and what was he aware of 21 years ago."
The trial is expected to last about eight days.
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