Three boaties were hospitalised after their vessel sank near Gulf Harbour on Friday afternoon.
Police said the trio had a "lucky escape" when their 5m fibreglass runabout began to fill with water near Tiritiri-Matangi Island.
A police spokesperson said they reported their sinking boat just before 3pm on Good Friday and, luckily, emergency services were able to pinpoint their location through one of the boatie's cellphone GPS.
Once the sinking boat was reported, Eagle and police maritime units were deployed. The spokesperson said volunteers on three Coastguard vessels worked with Eagle and found the three people in the water - all wearing life jackets.
"Eagle directed Coastguard Howick to the trio, who retrieved them from the water."
In a statement, the spokesperson said all three people were taken to hospital, "one of them in a serious condition from cold exposure".
Insp Martin Brown, of Tāmaki Makaurau, said it was "fortunate" the three boaties were wearing life jackets and had good communication.
"This is a really good example of how anything can happen when you're out on the water."
Brown said it's still unclear what caused the boat to sink, but said the trio "certainly weren't expecting it to happen".
"Nevertheless they were prepared and emergency services were able to come to the rescue."
Reminder for those hitting the water over Easter weekend:
- Always wear your life jacket.
- Take two waterproof ways to call for help.
- Check the marine weather forecast.
- Avoid alcohol.
- Be a responsible skipper.
