The fishermen, who had run out of drinking water three days ago, had set off an emergency locator beacon and were found 400 kilometres (250 miles) from Tonga by a searching New Zealand Air Force Orion.
Arrangements were made for the cruise ship the Albatros to change course, and it took more than nine hours to reach the stricken vessel, New Zealand Search and Rescue co-ordinator Ramon Davis said.
"When the Albatros rendezvoused with the fishing vessel, crew jumped into the water to swim to the ship," Davis said.
"Their fishing boat had been taking on water and was unlikely to remain afloat for more than 24 hours. The crew had also run out of drinking water.
They had been in a truly life-threatening situation."
The New Zealand Air Force crew who located the 11.5-metre boat dropped emergency equipment and a radio to the men, who were then able to communicate that they could not start their motor due to a flat battery.