Kaikōura charter boat tragedy: First helicopter pilot on the scene 'couldn't see anyone in the water'

The pilot of the first rescue helicopter at the scene of the Kaikōura charter boat that capsized killing five people says he saw no one in the water when he arrived.

"It's a terrible thing - it's something you don't want to see with people in the water," Kaikōura pilot Daniel Stevenson said.

An 8.5m boat with 11 people on board capsized off Goose Bay shortly after 10am today.

Five people were killed in a "collision" accident and six people have been recovered alive, police confirmed this afternoon in a press conference.

Earlier in the day, Kaikōura's mayor Craig Mackle said he believed the boat had hit a whale, but police would not confirm this.

Police divers have recovered the five people who did not survive and are now working through the formal identification process.

The passengers were believed to be part of a bird enthusiast group who had hired a charter boat for the morning.

Photo from a helicopter circling the upturned vessel in Goose Bay with one person seen on the hull. Photo / Supplied

Stevenson, the owner of South Pacific Helicopters, was listening to the maritime radio at work when he heard that a boat had capsized.

"I called (the) local police here to see if I could give a hand and we took off just to get eyes on the boat and (see) if there were any people in the water and see if we could help out at all," he said.

Pilot Daniel Stevenson circled the boat after dropping a diver into the water to search under water and the cabin of the upturned vessel. Photo / Supplied

The flight to the capsized boat took just under four minutes from the heli base and was less than 200m offshore.

"We arrived and there was a boat upturned and there was a man sitting on the boat," Stevenson said.

He then flew around the boat searching for people floating in the water but he couldn't find anyone.

Daniel Stevenson raced to the accident scene in a desperate attempt to find those who were missing. Photo / Supplied

Just prior to him arriving, a pleasure craft had arrived on the scene and grabbed the first group of people that were outside the boat and took them back to Kaikoura.

According to Stevenson, five people were rescued, and one person was left, sitting on the upturned hull of the boat.

The coastguard arrived shortly afterwards. They jumped into the water but couldn't get under the boat and requested a diver.

Stevenson flew back to Kaikōura, picked up a diver and hovered beside the upturned vessel.

"They jumped into the water out of the helicopter to see if there was anyone trapped inside the vessel," Stevenson said.

Three rescue helicopters were sent to the scene, one from Wellington and two Westpac Rescue Helicopters from Christchurch.

According to Stevenson, the sea conditions at Kaikōura were ideal, "a perfect day for boating" with just a light swell and little to no wind.

There had been whales in the area as he had been out whale watching with the fixed-wing aircraft.

"There were some humpbacks in quite close."

Daniel Stevenson raced to the accident scene in a desperate attempt to find those who were missing. Photo / Supplied

Where the accident happened was in water is 20m-30m deep, before it drops down to 500m in the canyon below, close in.

The tragedy is a big blow for Kaikōura and is keenly felt by residents.

"It is not very nice for a town like Kaikōura that relies on tourism. It will be the talk of the town. Everyone knows each other and there are quite a few charter operations.

"Initially everyone thinks it is a friend or something like that - it is a very tight-knit community when it comes to that kind of thing."

It is believed the occupants of the charter boat had come from all parts of New Zealand.

Police could not say who the charter was operated by. The skipper went to hospital but police do not believe he is injured.

"Our thoughts go out to friends and family of the deceased," the coastguard said.

Tracy Phillips, Maritime NZ principal investigator, said the organisation had sent two investigators from Christchurch to Kaikōura.

"Any investigation activity will commence only after rescue/recovery operations have concluded. We'll be conducting a thorough investigation under the Health and Safety at Work Act and the Maritime Transport Act and we'll do everything we can to support NZ police in their investigation."

Mackle earlier said he felt sick as the incident unfolded.

Richard Hill from Cods and Crays fish and chip shop told RNZ he had worked with the skipper on the boat before.

"He's a very safe man, there's no way he'd take any risks. So there's just got to be something sort of a freak of nature, I would have thought. A very sad day for Kaikōura really, just a shock," Hill said.

Kaikōura District councillor Lisa Bond said the incident was "incredibly heartbreaking".