A woman from Tauranga is in Wellington Hospital suffering from hypothermia-related problems after she jumped from a Cook Strait ferry late last night.
She spent an hour and a half in cold but calm seas before hitting the shoreline, about 300 metres from the ship.
Blenheim police say the 63-year-old went overboard off the Bluebridge Ferry Santa Regina fully clothed, with her suitcase.
Sergeant Mark Kirkwood says she only survived thanks to the efforts of a huge number of people who turned out in the early hours of the morning to look for her, including two Cook Strait ferries.
"I couldn't have asked for anything better, people using their personal vessels when someone is in need, that's what society is all about," says Mr Kirkwood.
Police, the Westpac rescue helicopter and various boats searched the area after the jump.
Fairfax NZ reported the woman was in a stable condition in Wellington Hospital and would be assessed by mental health officials.