A police spokeswoman said police were alerted to a "report someone's missing in the water" at 2.55pm.
Police, fire and ambulance are at the entrance of Omanawa Falls Rd and a helicopter can be seen flying above the area.
Tauranga Police sergeant Ben Gallagher at the scene said an operation was under way with police, ambulance and fire.
"At the moment it is an operation for a swimmer who had gone missing," Gallagher said."
The sergeant said the friends of the missing swimmer and any witnesses were still at the bottom of the falls and were in the process of being brought back up to the top.
Nearby residents had gathered at the scene after hearing a helicopter fly above their properties and over the falls.
One resident, who did not want to be named, said everyone knew when the helicopter flew past it was bad news.
"It is a nice place but it is dangerous," he said.
He believed it was the third time this year a helicopter had been called to an incident at the falls.
