Police say a sighting of a capsized boat off the coast near Levin was possibly "an optical illusion''.
A search was sparked after a Waitarere Beach resident called police to report a sighting of a small overturned boat shortly after 2pm.
The search was called off less than three hours later after surf lifesavers, three Coastguard vessels, a fixed-wing plane and a rescue helicopter were unable to find anything.
Constable Ian Hamblyn of Waitarere police said the man who reported the incident had seen the supposed boat through binoculars.
"He believed the boat was directly out from the surf club on the beach.''
Searchers scoured an area from the surf club to some 3km out at sea, where visibility from the beach ended.
Mr Hamblyn said police had also spoken to fishermen in the area, none of whom had seen anything.
"So basically everything's been stood down. We're pretty confident that there's no capsized boat.''
Mr Hamblyn said it could have been "an optical illusion''.
The man may have seen a fishing vessel or a log, a number of which had been coming down the Manawatu River following recent heavy rain.
"But he's done the right thing by alerting us because if it was an upside-down boat, we'd obviously want to get to it fairly quickly.''