The men, aged between 21 and 31, were charged with preparing to enter a foreign country “for the purpose of engaging in hostile activities,” an offense that carries a maximum penalty of life imprisonment.
They have been in custody since, and are not scheduled to face court until Monday.
“There’s no current or impending threat of a terrorist act to the Australian community arising from this investigation,” a police statement said.
Australia, a staunch U.S. ally, has been on heightened alert for attacks by home-grown radicals since 2014 and authorities say they have thwarted a number of potential attacks, while there have been several “lone wolf” assaults, including a cafe siege in Sydney that left two hostages and the gunman dead.
Approximately 100 people have left Australia for Syria to fight alongside organizations such as Islamic State, Australia’s Immigration Minister said last month.
Police said earlier this week that it was unclear where the men had planned to put the boat in the water. Indonesia and Australia share a maritime border, but it spans several hundred kilometers of open sea at its narrowest point.
The Australian Broadcasting Corporation said Melbourne-born radical preacher Musa Cerantonio, a vocal supporter of Islamic State who was deported from the Philippines to Australia in 2014, was among those charged.
Cerantonio, who converted to Islam from Catholicism at 17, was believed to be planning to join the militant group when he was deported for having “invalid travel documentation”. He was placed under surveillance but not arrested upon his return.