Police are hoping to recover the car linked to the disappearance of 11-year-old Michael Zhao-Beckenridge on Wednesday.
Police have been searching for Michael and his stepfather John Beckenridge since the pair went missing on March 13.
Michael was picked up by Mr Beckenridge from his Invercargill school during lunchtime. Mr Beckenridge had a parenting order against him forbidding contact with the boy.
There has only been one confirmed sighting of the pair since their disappearance and Mr Beckenridge's car, a blue Volkswagen Touareg, has since been found at the bottom of Curio Bay in Southland.
Track marks at the top of the cliff overlooking the bay led police to believe the car was driven at top speed off the cliff.
All evidence currently points to Michael and Mr Beckenridge being in the vehicle when it went over the cliff but police would continue to treat the case as an active missing person investigation, Southland Area Commander Inspector Kelvin Lloyd said.
The tidal forecasts showed the weather would be calm enough for the dive squad to enter the water over coming days, he said.
"The car, and what may be inside it, remains a crucial point to our investigation and we will be taking as much care as possible to recover it," he said.
"This means it will most likely take our expert team a considerable amount of time to recover it safely."
The Police National Dive Team would fly to Invercargill tomorrow to formulate a plan.
Floating equipment will be attached to the vehicle to float the wreckage and police would tow it out from the rocks to recover it.
Rough weather and tidal conditions had so far made it impossible for the car to be extracted.