Four men swam to safety on Saturday after their inflatable boat sank off Titahi Bay, north of Porirua.
Police say they were about 300 metres offshore when their rubber inflatable took on water and sank just before 10am.
Inspector Ken Climo says the men, who were aged 21 to 40, were wearing life jackets and swam to shore.
The ambulance service says one had mild hypothermia and was treated at the scene.
