"The vessel itself drifted about two miles ... so the husband would have done some fair distance," the Coastguard duty officer said.
The husband apparently decided pursuing the boat was pointless, so he also swam back to shore.
The boat was found 1.6km offshore. The couple and their boat were reunited. All three were fine - and the husband and wife were on their way home yesterday evening.
Some experienced divers suggest people have a "boatman" or person to stay on board while others dive, to prevent scenarios similar to yesterday's case.
Water Safety New Zealand also advises divers to study currents, wind, tides, swell, boat traffic and other conditions before heading out.