Aratere will retire by the end of August, to make way for demolition on its Picton wharf - beginning as soon as October.
It'll allow for infrastructure for new ferries, due in 2029.
Interislander Executive General Manager, Duncan Roy says more than two thousand-200 passenger bookings have now been transferred from Aratere to Kaitaki and Kaiarahi.
He says they're also starting formal consultation around possible impacts for staff.