The police national dive squad was called in today to join the search after Mr Barber became separated from his companions.
Police earlier said they held grave fears for the 19-year-old.
The river's condition at the time of the man's disappearance involved swift and dirty water caused by rain in the Tararua Forest Park, but police said river conditions had improved overnight.
An initial search was launched about 5.30pm yesterday involving the Life Flight helicopter, a jet boat, LandSAR search teams, firefighters, ambulance and police officers, family and friends.
Searchers had returned empty-handed last night after several hours of scouring a 3km stretch of the river north of Double Bridges to a point near Rathkeale College.
Life Flight crewman Dave Greenberg said the river late yesterday afternoon had been "flowing fast and there was a lot of water''.
He said the helicopter carried three searchers and a pilot and had descended at times to within 100 feet of the river surface during an intense search that lasted about an hour.
The helicopter had made three search passes of the 3km stretch of the river.