Bad weather is stalling efforts to confirm whether a boat located beneath Tongan waters is the Princess Ashika, which sank last Wednesday.
At least 149 people were on board the ferry when it capsized 86km northeast of the Tongan capital of Nuku'alofa. Two bodies and 54 survivors have been found, while 93 people were presumed drowned after being trapped in the vessel.
The New Zealand dive squad had planned to send a remotely operated vehicle (ROV) down to the boat, which is sitting 110m underwater, but poor weather was preventing that, dive team head Lieutenant Commander Andrew McMillan of the Royal New Zealand Navy said.
"There's a lot of wind around and that's going to prevent us from conducting our ROV operations," he told Radio New Zealand.
"Our depth limit is 50m, we can't get down there with the divers, so the ROV is our only option. It carries a video camera with it, so it will actually give the operator on the surface a live picture of what's down underneath."
Mr McMillan said once the team had confirmed the boat's identity by reading the writing on it, they would remain in the area to try to establish possible reasons for its sinking.
"We'll do a full survey of the vessel and provide those pictures to the Tongan Government."
The surveyor in charge of carrying out checks on the ferry said it was not seaworthy, but Tongan Transport Minister Paul Karalus has maintained it was.
He resigned on Tuesday but denied he was admitting responsibility.
He said he had resigned because his ministry was the subject of a royal commission of inquiry.
Tonga's Prime Minister Feleti Sevele has said the sea worthiness of the ferry will be investigated by a commission of inquiry, though he noted that he had himself seen the ferry's certificate of seaworthiness.
Meanwhile, deep sea recovery expert Bill Day said it was possible to recover bodies from a depth of 110m, but at a huge cost.
" That sort of stuff's done all day around the world, but you're talking about equipment that isn't in New Zealand and will have to be brought into Tonga," he said.
"It's hundreds of thousands of dollars a day to run an operation like that."
Mr Day said he believed the cost, the potential dangers for the divers and the months it would take to complete the recovery meant that it was unlikely to happen.
"Very sad as it is, this may be one that's impossible to do."
