Police divers will today join the search for a man who went missing while swimming at Omanawa Falls.

The police national dive squad is expected to arrive at Omanawa Falls today to help search for the man who went missing while swimming at the falls yesterday afternoon.

A police spokeswoman said police were alerted to a "report someone's missing in the water" at 2.55pm.

Police search and rescue responded just before 3pm, with police, fire and ambulance staff also attending.

Emergency services at the scene after reports of someone missing in the water. Photo/George Novak

The Whitianga-based crew of the Auckland Westpac Rescue Helicopter was called to help with the search and rescue of four young adults who went missing at the bottom of the waterfalls.

A rescue helicopter arrives at the scene. Photo/George Novak

The crew was initially tasked to retrieve three patients with one still missing but two of the young people managed to walk out themselves.

Pilot James Tayler said they helped a 21-year-old woman from the falls in what he described as a "challenging" rescue.

Intensive Care Paramedic Casey Drum had to be lowered from a height of about 200 feet into a very steep and narrow gorge at the bottom of the falls.

When Drum rescued the woman she was in shock and suffering mild hypothermia, and was taken to Tauranga Hospital.

Bay of Plenty District Health Board spokeswoman Diana Marriott said the 21-year-old Hamilton woman was in a stable condition in Tauranga Hospital's Emergency Department last night.

Tauranga City Council staff limited access to the area overnight before the police national dive squad continued the search for the missing man on Monday.

At the scene, Tauranga Police sergeant Ben Gallagher said a group of people got in trouble at the bottom of the falls.

"They had been swimming at the falls and one person has not resurfaced," he said.

Friends of the missing swimmer and witnesses at the bottom of the falls were brought to the top by truck or helicopter which landed on a neighbouring paddock. Many were wet and had towels wrapped around their shoulders.

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.

Council staff were limiting access to the area overnight, before search and rescue teams resumed their search this morning.