A police spokeswoman said the dive squad completed its search on Monday and was unable to locate the man.
"A helicopter will search the river from the air this morning and the Coastguard will assist with the search this afternoon."
Police were called when the man's friends could not find him after he went swimming near the Waimakariri Bridge at the weekend.
The dive squad began its search on Monday morning.
Their search effort has focused on the area between the State Highway 1 bridge and the Old Waimakariri bridge.
Local runanga have placed a rahui on part of the river.
The Kaiapoi Coastguard crew hopes the swimmer will be found.
President Logan Pryce said they took a boat up the river late on Saturday night as far as the bridge, but were unable to find him.
"We always hope for a good outcome when these sorts of things happen but hopefully we can bring this guy home today would be nice."
He said river conditions were fine at the time.
Police said anyone with information about the incident should phone 105 and quote file number 210130/5446.
