Five people have been pulled from the water after the boat they were in capsized in Tasman Bay.
One person has been treated for a minor injury and is being taken by rescue helicopter to Nelson.
Police were alerted at 12.30pm that people were in trouble at Split Apple Rock near Kaiteriteri, 150 metres offshore.
The Nelson Rescue Helicopter, NZ Coastguard, Fenz, and St John ambulance are all at the scene.
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According to the Coastguard, a small fibreglass runabout got into trouble but it is "not sure why".
The five people were picked up by a water taxi that regularly plies the waters to the nearby Abel Tasman National Park.
The boaties were all found cold and in shock and were taken back to Kaiteriteri beach where they were being treated by paramedics.
The weather in Tasman Bay has been fine and calm, and there are no strong winds or any significant swell in the area.
The submerged fiberglass boat was being towed by the Coastguard to Kaiteriteri two kilometres away.