Rottnest Island off Perth will be a coronavirus quarantine zone for 800 Australians onboard the Vasco da Gama, as the number of cases from other cruise ships continue to rise.
The vessel is scheduled to arrive in Fremantle on Friday, carrying 950 passengers and 550 crew.
Premier Mark McGowan says all foreigners, including 109 New Zealanders, will remain onboard until they can fly home.
But 800 Australians, including 200 locals, will be transferred to holiday hotspot Rottnest for 14 days of isolation.
"I'm not going to take any chances," Mr McGowan told reporters on Wednesday.
Dean Brazier, managing director of the ship's owner Cruise and Maritime Voyages Australia, said guests had not reported health issues.
"When they arrive, our guests will have been at sea for 13 days straight without disembarking," Mr Brazier said.
"We are disappointed that they will now have to wait a further 14 days until they can return home."
The Artania cruise ship, which was due to arrive in Fremantle for refuelling, has about 25 passengers and crew with respiratory symptoms.
A former passenger tested positive to COVID-19.
More than 800 foreign passengers and 500 crew are onboard, and the ship has requested assistance, which WA health officials are delivering.
Meanwhile, the Magnifica departed Fremantle on Tuesday after everyone was kept onboard during refuelling but was blocked from docking in Dubai, so headed back.
Both the Magnifica and Artania must remain at anchor off the coast, and nobody will be allowed to go ashore unless they have a life-threatening emergency.
Mr McGowan has asked the Commonwealth for assistance to ensure the ships do not try to declare an emergency to disembark.
Josh Wilson, federal member for Fremantle, which also covers Rottnest, told AAP the McGowan government had taken decisive action.
But it was time for the federal government to tell the public what lessons it had learnt from the Ruby Princess debacle in NSW and what it was doing to stop that happening again.
The number of coronavirus cases in WA has surged by 30, bringing the total to 205, including five from cruise ships.
WA has recorded 47 cases from cruise ships in total.
The COVID-19 testing regime has been substantially expanded, including police and people with symptoms who have been in high risk settings.
Testing will also be done where there are workplace outbreaks.
WA has become the first state to restrict takeaway alcohol sales for at least two weeks in an effort to prevent the healthcare system from being overburdened.
Mr Dawson said it was not prohibition, given people could buy more than 100 standard drinks a day.
The premier also promised liquor stores would not close.