Below the surface: What really happened to scuba diver Goy Thongsi?

Over summer, we’re revisiting some of the biggest and best podcast series from the NZ Herald network throughout 2023.
Today, we’re resisting Chasing Ghosts: Below the Surface.
Bua-Ngoen ‘Goy’ Thongsi vanished below the punishing swell of Motunau in North Canterbury eight years ago while out scuba-diving. In the years that followed investigations were opened and closed, witness accounts were inconclusive and her cause of death was eventually ruled undetermined by a coroner who questioned whether the real story had come out yet. In this season, Open Justice reporter Hazel Osborne looks at whether there is more below the surface.
Goy Thongsi’s friends slept beside her body at a Buddhist temple for three days and three nights after she died.
The scuba diver’s small frame was covered and adorned with white lilies, her favourite flowers, while her loved ones told stories of her life, sang songs, laughed, and cried.
They were there to be with her, to show her spirit she wasn’t alone even in death.
It’s been eight years this month since they gathered at that Christchurch temple, a place where they all used to spend most Sundays together while she was still alive.
Eight years since their smiley, hardworking and recently separated friend went scuba diving and never came back.
Despite extensive efforts, including three police investigations and three coronial inquests, what really happened that day at Motunau Beach, off the North Canterbury coast, remains a mystery.
Coroner Brigitte Windley has left the cause of death as undetermined, saying she’s not confident the real sequence of events has been fully disclosed. She also doesn’t believe it was a diving-related death.
“I was not satisfied I had received a sensible, coherent and complete narrative of the events surrounding Ms Thongsi’s death.”
That means many questions about that day remain unanswered, especially for her loved ones, including her friend Yuawari Somnuk and Somnuk’s sister Kwan Nicol.
“I believe the police did their best at that time, but for us, we still have questions, how she died and why?” Nicol said. “One year two years, why, why, why,” Somnuk added.
Thongsi was just 37 when she died.
She was funny, ambitious, hardworking and loved by the Thai and Buddhist communities in Christchurch.
The youngest in a large family, she moved to Christchurch in 2007 after falling in love with local man Barry Easton.
Newly married, she quickly built strong connections, including at her temple in the suburb of Shirley, and was known as someone who was always on the go and who worked hard – both day and night.
But, her relationship didn’t last and after separating from her husband she moved in with Somnuk and her family. Somnuk’s daughter Nisa loved Thongsi like an aunty.

As she started to move on with her life she found a new passion in scuba diving.
A language barrier prevented her from passing a Dive HQ course in Christchurch in 2013 but she’d recently completed an entry-level dive course in Thailand, just months before her death.
Somnuk said she was fearful of Thongsi’s fervent dedication to scuba diving while Nicol described her as “brave” for pursuing the hobby as she found her feet following the separation.
Along with a hobby, Thongsi had a new man in her life, although the relationship was secret, and she was out with him and several others on the day she died.
The sun had barely risen when Thongsi and her four companions, skipper David Avei, Brent Chappell, Ina Tekii and Wally Mohi took the winding road out to Motunau on February 8, 2015.
It was Avei she was seeing – something they had kept hidden from both his wife and her ex-husband. Avei later told the court he had no intention of leaving his wife.
Her ex-husband later told police that she had confided in him in the days before her death that she might be pregnant. However, no medical records corroborated a pregnancy.
Avei said she hadn’t mentioned any pregnancy but later said in his evidence at the inquest he would have questioned it because he “wasn’t sure I was the only person she was sleeping with”.
The skipper was one of the last few people to see Thongsi alive that day. The group was diving for a customary permit of 50 crayfish at the popular dive site.
Mohi, who was hungover on the day, had asked Avei, Tekii, an old army mate of the skipper, and Thongsi to “fish the permit”. Mohi and Chappell weren’t diving.
Neither Mohi nor Tekii knew Thongsi, but Tekii was designated as Thongsi’s “buddy” – a safety precaution observed by scuba divers to make sure a person has support if something goes wrong in the water.
Thongsi entered the water at the second site of the day at around 9am, just 2km off the shore and at a depth of 9 metres.
Chappell, who Thongsi knew through her ex, helped her into her gear while her buddy, Tekii, had left her on the boat, descending below the swell with an empty buoyancy compensator device (BCD).
When Tekii resurfaced 31 minutes later, Thongsi was dead.
The accounts of what really happened on the boat were varied but the version deemed most accurate by the coroner was from Chappell. He saw Thongsi backroll into the water before popping back up again.
Her spare regulator had inverted and was leaking air, so, with an outstretched arm Chappell brought her into the side of the boat.
Avei helped unstick the breathing apparatus, returning to the boat wheel, but something wasn’t right.
Chappell, who guided Thongsi to the back of the boat, said it was like she was looking right through him.
“Like nobody was home.”
When they let go of each other’s hands Thongsi sank from the man’s sight – it was the last time she was seen before her body was recovered from the sea floor two days later.

Thongsi’s death was the subject of a three-stage coronial inquest in 2018 that left Coroner Windley, with more questions than answers.
“It is a matter of considerable regret that after three inquest hearings and three police investigations, I am left unable to make firm findings as to the cause and circumstances of Ms Thongsi’s death,” she said in a decision, released on February 26, 2021.
“An open finding is relatively rare in this Court, and rarer still in a case where a deceased has died in the company of three companions.”
“Unfortunately, and sadly for Ms Thongsi, […] I cannot be satisfied, even on the balance of probabilities standard that applies to my jurisdiction, that the sequence of events which led to Ms Thongsi’s death has been fully disclosed.”
Coroner Windley believes Thongsi was likely to have died before she sunk from sight.
She said it was unlikely to have been the result of equipment failure, lack of air or an external but natural event, such as a shark attack.
It was also unlikely to have been related to migraine medications she was prescribed or her lack of diving experience.
“As to the circumstances of Ms Thongsi’s death, I find only that her death occurred in the context of a recreational scuba diving trip, but for the reasons set out above, the evidence does not allow for a finding that her death was diving related.”
Witness evidence during the hearings that spanned over 2018 showed irreconcilable accounts of what really happened on the boat that late summer morning. The accounts of the men were vital to the Coroner.
A final police investigation galvanised by new evidence during the third inquest hearing concluded in 2020.
Police believe it was divers’ error, and inexperience, that led to her death.
However, all evidence that could assist them in finding concrete proof of how Thongsi died disintegrated with the fragmented accounts from the men and the medically inconclusive findings.
No criminal liability has been found in relation to her death.
Professor Des Gorman, a diving medicine expert and Australian Navy-trained diver, was called as an expert witness during the inquest.
Breaking his silence for the first time since Coroner Windley’s 2021 decision, Gorman believes Thongsi, and her loved ones, deserve answers.
“I feel very deeply for her and her relatives and the people who cared about her because I don’t believe justice has been done and at the very least they deserve an explanation of how she died that is credible and as it stands the received history is not credible.”
When Thongsi vanished below the surface, Avei searched for her body – but it only lasted a few minutes.
He told the Coroner he had four minutes before he knew she was gone forever, but spent less than that when he got in the water to find her, coming up from the short “rescue” dive because he had failed to turn his air on.
He never returned to the water to search for her – and a number of skilled divers, including Gorman, said the brief search was unusual in the scuba community.
In Coroner Windley’s findings, she noted the same thing.
“I heard evidence during the inquest hearings that is far more common for the companions of a missing diver to remain at sea searching, even after all hope of the diver being found alive has passed.”
It was Tekii who called emergency services, more than an hour after her disappearance.
Despite being urged to stay put at the site where Thongsi had gone missing, the group stayed out for just an additional hour – opting to return to shore with the window of time limited to high tide.
This was a move that went against the police call takers’ advice who said they “had a duty” to Thongsi to stay and search.
Fisheries officer Belinda Symon was one of the first to encounter the group back on land. She says Avei told her Thongsi “sunk like a stone” and that he realised she was dead “from the moment she left the surface” but the skipper later denied both comments.
Symon said Avei and the group appeared to be shocked and distraught but was surprised they had returned to shore so soon after Thongsi’s disappearance.
She told the inquest during the second hearing in August 2018 that police never contacted her, a call she had been waiting years for.
Symon wasn’t the only person surprised by how little time the men spent searching for Thongsi.
Local technical divers Peter Taw and Jon Feild collectively hold a long list of qualifications, thousands of dives and decades of experience.
They say there is a culture of Motunau – a “she’ll be right” mentality of a dive site that can turn in an instant.
Feild, who has completed over a thousand dives during decades of scuba, said being by the side of a diver with Thongsi’s experience at Motunau, was “critical” and she should have been watched “like a hawk”.
Both Feild and Taw say scuba divers can often deviate from standard practice, what has been taught when they qualify, and in its place habits are formed that could become dangerous.
While neither man was directly involved in the case they question how Thongsi could lose her life – and how short the search was to find her afterwards.
“There seems to be a missing piece of information that we can’t put our finger on but if we had that piece of information, it would all make sense,” Taw said.
“If I was on a boat with some buddies and one of them was struggling or in trouble, I would do everything in my power, give them my last breath to try and rescue them.
“I would dive until I couldn’t dive anymore to try and find them if not to rescue them or secondly to maybe bring the body up to save the trauma of not knowing what happened to her.”

Thongsi’s body was recovered from the sea floor by the police national dive squad on February 10, approximately 60 metres from where she was last seen.
The condition of her body meant, to Pathologist Dr Martin Sage, determining a cause of death was futile.
When she was found, her gear was intact – the only pieces missing were her wetsuit hood and weight belt.
The PNDS tested her gear, nearly all brand-new except for her BCD which was second-hand and serviced in the months leading up to her last dive.
It was initially thought by police her gear had no impact on what may have caused her death, but the inverted regulator was mentioned at a later date.
In 2015 police opened an investigation into Thongsi’s death after a local Sergeant referred the case to the Criminal Investigation Branch (CIB).
Police said in their February 2020 conclusion that their initial investigation could have been more thorough.
The three coronial hearings were conducted in June, August and December 2018 in the hope of determining how she came to lose buoyancy and how she died.
New evidence from a man with name suppression, which came to light after media coverage of the second hearing, would give pause to the process.
The witness claimed Chappell had visited him the day Thongsi had gone missing and said the group had “let [Ms Thongsi] go” after realising she had died. The man added that Chappell “hoped her body would not be found, or at least not found for some time, so it would not be possible to determine what had happened to her”.
Coroner Windley directed this evidence to police inviting them to consider whether any further criminal investigation was required.
Police re-opened the case again but in November 2018 told the Coroner “no criminal charges were under contemplation”.
Coroner Windley wanted to test the evidence of this witness under oath, calling him at the third, and final hearing.
His evidence was rejected by the group on the boat, and the subsequent police investigation concluded no criminal liability in the case of her death.
The final police report concluded, in summary, that Thongsi was in a panicked state entering the water, descended “willingly” but became nervous after her stuck regulator was fixed. When she descended the issue arose again.
Weighed down by her weight belt she panicked and was unable to find her spare regulator, drowning in the process.
They said her buoyancy came from her “finning” on the surface, and she was “negatively buoyant”.
Expert witness, Professor Gorman believes the conclusions reached by the police, and the accounts of the men “don’t add up”.
“If you look at the consistent bits of the story, it doesn’t add up and so if you look at the sort of likely causes of death in a diver in this circumstance, none of these stories you can actually manipulate in a way to say this is how this diver would have died.”
The justice system, and the coroner’s court, are made up of so many moving parts.
At the beginning of each inquest, a coroner reminds the court why the hearing is being held in the first place. It is for the person at the centre, the deceased.
Independent victim advocate Ruth Money has witnessed this first-hand, and the toll it can take, pushing many people to breaking point.
She doesn’t believe there has been justice for Thongsi, or her loved ones.
“Reading that decision delivers nothing but questions and further harm for Goy’s family and friends and that’s the polar opposite of what an inquisitorial inquest is supposed to achieve,” Money said.
“There has not been justice for Goy, my heart hurts for her family and friends I am shocked and dismayed how people can go on the record and consistently change their evidence.”
So for now, as another anniversary of her death passes by, the question of what happened to Thongsi remains unanswered.
All of the men who were on the boat were approached for comment for this podcast and article. Chappell was the only one to respond, saying he didn’t want to comment.
Follow Chasing Ghosts on iHeartRadio, Apple Podcasts, Spotify or wherever you get your podcasts, to hear the conclusion of this season, and the other seasons of the series.