North Yorkshire Police said it was "very unusual" for missing Ben Clarkson not to be in touch with his friends and family and they are very concerned about his welfare.
Ben, 22, disappeared after a night out with friends in York.
Inspector Jo Brooksbank said her officers have already carried out searches of his likely route from Fibbers nightclub on Stonebow, where he was last seen early on Sunday morning, to his home in Heworth Green.
Underwater search teams have also searched the River Foss in the areas between Iron Bridge, Huntington Road and Foss Basin.
Ben was wearing dark skinny jeans, a grey t-shirt with eiffel tower logo and grey pumps with a white trim.
A RIVER rescue team will join the search for a missing York man today.
Ben Clarkson, 22, of Heworth, was last seen outside Fibbers nightclub in Stonebow at about 3.30am on Sunday, and police said it was unusual that he would be out of contract with his friends and family for so long.
This morning, the Yorkshire And The Humber Marine Unit - which conducted a series of searches of the River Ouse for Megan Roberts in January and February - have confirmed they are to be deployed to York to search for the former York St John University student, who now works at Music Room in Lendal.
A spokesman for North Yorkshire Police said the team would be searching the River Foss throughout today, with land searches of the river banks also taking place, but said the river searches were just one line of investigation.