The New Zealand and Australian navies are formally planning a joint response to aid in the search for those listed as missing from Tonga's ferry disaster.
It follows a request from Tonga's Prime Minister, Feleti Sevele.
He says there is little chance of finding survivors.
The Defence Minister, Wayne Mapp, says staff are looking to see what can be done for what looks likely to be a tragic task of recovering people who drowned.
He says the navies are working together because of the challenge of the task, because the depth of water where the ferry sank could be 100-metres.
Dr Mapp says the response requires a trans-Tasman approach.