The stranded orca calf being cared for in Porirua is being moved out of a temporary pool and into the sea pen for health reasons.
The orca, named Toa, was found stranded on the rocks 12 days ago.
For over a week, the orca has been held in a pool beside the sea after it was shifted due to bad weather conditions and then could not be shifted back because the water was contaminated.
Department of Conservation marine species manager Ian Angus said vets now believe it is best for the orca's health to be in the sea.
"The calf has injuries to his pectoral fins and tail fluke and needs to stretch out in deeper water. It also has an issue with an inflamed eye which vets believe would respond better in salt water," Angus said in a statement.
He said DOC had been seeking assurances about the water quality in the harbour before allowing people and the orca back into the sea.
The Plimmerton Boating Club site remains closed to the public to reduce stress for the orca calf.
DOC still wants to hear about sightings of orca pods in an attempt to track down Toa's family so it can be returned to its pod.