A relative posted on social media today that he left for the trip around 5am yesterday and his car was found to still be near the boat ramp last night.
The Police Maritime Section, Police Eagle helicopter and a Coastguard fixed-wing plane all joined in the search this morning. The focus of the search was the areas of Rotoroa Island, Waiheke Channel or the Firth of Thames, said Coastguard Northern Office regional manager Jonny Bannister.
Police had described the jetski as a two-person Seadoo with a black hull and white and gold topsides.
Inspector Homan had asked for anyone in the area to be extra vigilant and report any sightings of the jet ski or floating debris.
"Police would like to extend their thanks to everyone who has assisted with the search and our condolences go out to his whānau," he said this afternoon.
The death will be referred to the Coroner, police said.