The small outboard motor-powered boat was carrying a family of five, when it was flipped by a wave while attempting to cross the Taieri Mouth bar on Saturday afternoon.
Taieri Mouth resident Lawrence Clark raced to the scene on his jet-ski following a phone call from a neighbour.
"I could see three surfers on surfboards back at the boat.
"The one who was missing was a little girl. She was trapped inside the overturned boat.
"One of the surfers managed to retrieve her. She looked lifeless. It was harrowing."
Two of the surfers were young doctors and they performed CPR on the girl, on top of one of their surfboards, he said.
"They kept doing it as I towed them back to shore.
"There was a very strong current running north and with the waves coming in, it was very disturbed with big swells and lots of white water.
"It was very tricky to get them in without going over ourselves."
The surfers continued CPR on the beach until the rescue helicopter arrived, he said.
Mr Clark praised the surfers for their heroism.
"In those conditions — the pressure and the stress — they were amazing.
"The boat was 98% submerged and there was a huge swell rolling through, so for them to go underneath the boat and pull that little girl out would have been very risky, but heroic at the same time."
A police spokeswoman said one of the children died in Dunedin Hospital and another child remained in intensive care in a stable condition.
Two adults and a third child were released from hospital yesterday.
The boat has been recovered and Maritime NZ has also started an investigation.
Local iwi placed a rahui (a form of tapu restricting access to, or use of, an area) around the Taieri Mouth until 9am today.
Emergency services personnel thanked the people who came to the aid of the family.
The incident has left some in the Taieri Mouth community asking what more needs to happen before something changes at the dangerous waterway.
Resident Trevor Griffin was not involved in Saturday’s rescue, but said he believed it was similar to many others he had been involved in at the mouth over the years.
"It was so preventable — that’s what’s so upsetting.
"We do need to start looking at better measures. We can’t have the loss of a child and not try to make more changes.
"Hopefully, people might start thinking about it more now."
He was among many spoken to by the Otago Daily Times who believed the conditions were not suitable for taking a boat over the bar on Saturday.
"There was a 3m to 4m long-period swell on a low tide, so what happens is the water is really flat and then you get these massive waves coming in from the sea.
"It looks really calm, but it’s not. It’s perfect for surfing but it’s not for boating," he said.
Even boaties who were experienced at crossing the bar sometimes got into trouble, so it was important those who were inexperienced in this particular waterway knew the danger they were putting themselves in, he said.
"It’s all about seamanship really.
"Maybe we could do something like have more bar-crossing seminars. It doesn’t mean nothing’s going to go wrong, but you’ll have a much better idea of the type of weather patterns you want to get across safely."
Two sessions on crossing the bar safely were held at the end of last year, attracting about 250 people.
Mr Griffin also suggested putting up warning signs saying "this is a bad weather forecast for crossing the bar — if you see it, don’t even attempt it".
Brighton coast stalwart Colin Weatherall agreed education was the key to saving lives.
A web camera was "very close" to being installed at the Taieri Mouth bar, which would allow boaties to see where the bar was and what the wave conditions were like, he said.
It aimed to prevent accidents and assist water rescues.
Mr Griffin said short of closing the mouth to all but commercial fishing crews, there was little else the community could do.
"Maritime NZ probably have the power to do it, but closing the mouth would not go down well with amateur fishermen."
