Salvors hope to start pumping fuel oil from the last main tank on the container ship Rena on Thursday.
The vessel has survived another night in rough seas intact. It went aground on the Astrolabe reef on 5 October.
Svitzer Salvage says crews have been assessing when they can start to drain the last of five large oil tanks.
Conditions were considered too dangerous on Wednesday night.
Spokesperson Matthew Watson says salvor have also been working to remove smaller tanks containing oil and other liquids.
