Wellington District search and rescue co-ordinator Jonathan Westrupp said the person indicated their boat was taking on water with two people on board.
An interislander ferry joined the search for the missing boat on Monday night.
“They failed to respond after several further transmissions, and a search was immediately activated and multiple vessels were deployed to the area.
“We’ve found no objects of interest in the strait or during searches of the shoreline or boat ramps, and no boaties have been reported missing or overdue.”
Westrupp said police were working to determine the mayday call’s source and veracity.
“We continue to ask the public to notify police should they notice anything unusual in the Cook Strait area or become aware that someone is overdue.”
Wellington police thanked the public, Royal NZ Navy, Royal NZ Air Force, the Rescue Co-ordination Centre, Coastguard Wellington, Wellington Airport Fire Service, Interislander, Bluebridge, Centreport, Seaworks and the media for their support.
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