Navy amphibious landing ship HMAS Choules is taking people to Manus Island to assist set up the expanded asylum seeker processing centre.
The vessel will be used to accommodate defence and other personnel performing this work but not asylum seekers.
Defence said HMAS Choules was part of an Australian Defence Force (ADF) Joint Task Force assisting the Department of Immigration and Citizenship (DIAC) to increase the capacity of facilities on Manus Island.
The 16,000 tonne vessel left Cairns on Tuesday.
Defence personnel are conducting site surveys and works on Manus Island ahead of putting up accommodation facilities.
"The tasks have included site survey works for future DIAC facilities, remediation and preparation tasks by plumbers, electricians and carpenters for the site," defence said in a statement.
RAAF C-130J Hercules transport aircraft have delivered construction and support equipment to Manus Island.
Defence says it's playing no role in managing or providing security to the DIAC facilities.
