The boat was near Matiu/Somes Island when it started taking on water during a fishing trip. Photo: RNZ / Rebekah Parsons-King
Five boaties are still alive because they were wearing life jackets after the boat they were on sunk, police say.
Police said the boat, Hustler, started to sink between Matiu/Somes Island and Seaview Wharf near Wellington around 7pm on Sunday during a fishing trip.
Those who had been on the boat were left treading water while two swam to shore and called for help.
Three of those rescued ended up getting hypothermia from being in the water for about an hour.
Sergeant Richard Kennedy of Wellington Police maritime unit said wearing life jackets "saved their lives".
At least one was not a strong or confident swimmer, so the life jacket made the difference between life and death, he said.
Hustler's skipper Kerry McIvor, agreed.
"We had the life jackets and we had our mobile phones to call for help if we needed to," McIvor said in the press release.
McIvor said he had anchored between Matiu/Somes Island and Petone to fish when the boat started taking on water.
"We had a bilge pump but it couldn't cope with the amount of water."
McIvor said the anchor was pulled up and they started "motoring" back to Seaview but the water on board was just too much.
"The stern went under and the boat sank a few hundred metres off Seaview Wharf and all of us ended up in the water.
"My mate and I swam about one kilometre to shore, climbed out onto Seaview Wharf and raised the alarm.
"My mate held his mobile phone above his head the whole way."
It was a timely reminder to have a water-proof bag to hold mobile phones, or to have a radio or beacon on board in case of an emergency.
The boaties were rescued by police and taken to hospital for treatment.
Police said they had believed the boat had sunk but around 9am on Monday, a partially submerged boat was found drifting in the shipping lane at the entrance to the harbour.
Police were called to remove it and discovered it was Hustler.