The "incredible initiative" of a sinking boaties' wife saw him rescued within two hours after she provided Coastguard with a location from a mobile phone locator app.
The man rang his wife just before midnight yesterday from an area around Moturoa Island, in the Bay of Islands, saying his 4.7 metre powerboat was sinking and the water was already "above his knees", Coastguard Northern Region said in a Facebook post.
The phonecall was cut off as the man's boat sank from under him and he was not able to provide an accurate location, the post said.
However, his wife "showing incredible initiative", phoned police and supplied rescuers with a map from her Find My iPhone app, which linked to her husband's iPhone.
"The details were sent through to Coastguard and, although the details on the map were vague, the team were able to triangulate a likely GPS position to begin searching," Coastguard said.
A team from Coastguard Bay of Islands, on board Bay Rescue II, discovered the man less than two hours after the initial phonecall.
He was in the water, "cold and shaken, but otherwise unharmed", Coastguard said - and 0.2 nautical miles from the 'guess-timated' position.
"Thanks to the quick thinking of the man's wife and the skills of Coastguard searchers, a potentially tragic outcome was avoided."
The boat was recovered by the Harbourmaster this morning.