A crew member on a ship off the coast of Karratha has been diagnosed with COVID-19.
WA Premier Mark McGowan announced the new case at a press conference on Monday.
A man aged in his 50s became unwell on the cargo ship Aquagenie on April 8 and was tested, returning a positive result the next day.
A smaller ship was sent out to collect the crew member on Sunday and he was taken to Karratha Health Campus.
He will now be flown to a dedicated isolation ward at Royal Perth Hospital for treatment.
No-one else on board the Aquagenie is showing symptoms of the virus, but the captain has been refused permission to dock at port.