The Coastguard then arrived and two police officers entered the water and retrieved an exhausted man still clinging to the boat, the spokesperson said.
Ambulance staff helped those rescued, who were suffering from hypothermia and had swallowed sea water. Three were taken to Wellington Hospital for observation.
The Westpac Rescue Helicopter also attended the rescue.
Police were pleased everyone was safe, but noted lifejackets, while being available, were not being worn, the spokesperson said.
"With winter just behind us and the water becoming more attractive for recreation, now is a good time to remind all boaties of the importance to always wear a lifejacket."