A remote-controlled underwater vehicle is to be used in an attempt to identify about 50 objects on the Bay of Plenty sea floor that are thought to be containers from the Rena.
About 300 containers remain unaccounted for since the cargo ship grounded on the Astrolabe reef last October.
The salvage company Braemar Howells will complete an 800 square km sonar sweep of the seabed this week.
Operations manager Neil Lloyd says the underwater vehicle will be fitted with a video camera to identify the objects.
He says if they are confirmed as containers they will be tagged by the underwater vehicle and attempts will be made to retrieve them.