A cruise ship bound for the Bay of Islands saved six Tongan fisherman, who had not had water for three days, from their boat.
The fishermen are today in good health after being checked by the cruise ship's doctor.
New Zealand's Rescue Coordination Centre alerted the German cruise ship, the Albatros, at 5am on Saturday after the fishing vessel crew set off an emergency beacon.
The fishermen were about 400km south-west of Tonga.
The Albatros diverted 300 kilometres to help the fishermen. It got to the fishing vessel about 2.30pm on Saturday.
A New Zealand defence force plane dropped emergency supplies - including a radio, water and food - to the men, who were without water for three days. The Orion crew could see two men on deck, who were safe and well, Air Commodore Darryn Webb said.
New Zealand Rescue Co-ordination Centre senior search and rescue officer Greg Johnston said when the cruise ship arrived it was clear the boat was not leaking, but rather there was engine failure.
"It was wallowing around in the swell a little bit, so it was taking water over the sides, which was entering the boat and they had no means of pumping it out.
"They were getting into a fairly dangerous situation and the cruise ship's captain decided that it wasn't safe to leave people on board, so they transferred them to the cruise ship."
The cruise ship was expected to arrive, with the fishermen, in Auckland about 9pm on Monday.
Mr Johnston said the men were seen by the cruise ship's doctor and there were "no concerns for their health".
Once the fishermen were safely on shore, other services would step in and take care the men from there, he said.
Senior Search and Rescue Officer Ramon Davis said the fishing boat was unlikely to remain afloat for more than 24 hours.
"They had been in a truly life-threatening situation," he said.
Mr Johnston said EPIRBs (Emergency Position Indicating Radio Beacon) were a brilliant tool for getting people out of a distressed situation.
* An earlier version of this story said the boat was sinking and the fishermen tried to swim to the cruise ship. These details, which came from authorities on Sunday, were later found to be incorrect.