Christmas Eve in 1953 holds a tragic place in our nation's history. Many over a certain age can recall where they were, when they learned of the Tangiwai disaster.
One hundred and fifty-one people died when a packed express Wellington to Auckland train plunged into a raging Whangaehu River just outside Ohakune in the central plateau.
It was New Zealand's deadliest rail tragedy, caused by a relatively unknown threat - a lahar released from Mt Ruapehu's Crater Lake.
This Sunday, commemorations will take place to mark 70 years since the disaster.
Journalist Hamish Williams, who produced and presented the podcast series Tangiwai: A Forgotten History will be there, as will Callum Mahy, whose father was on the train that night and has been instrumental in commemorating those who were not so lucky.
Mahy told RNZ's Summer Times his father John was on one of the few carriages left on the track after the rest of the train derailed.
"But prior to that he was actually in the second carriage from the main engine, which obviously plunged into the river.
"So, his memory of being transferred from second class to first class, and then obviously the accident happening… getting out of the train and seeing it pitch black and not being able to see anything. So it's hard to explain what he saw."
His dad was just 15 at the time. He was travelling with his older sister, who was 17.
They had first-class tickets, so should have been at the back of the train from the time it left Wellington, but their seats had been taken by someone else.
"So they were in the second-class carriage, and the guardsmen came up to them - we presume it was [around] Taihape or Waiouru - and said that they had the first-class seats for them.
"So they thought, well, they might as well finish the trip in style and they went to the first class-seats - and of course, 15-odd minutes later, the accident happened."
John did not speak much about the experience until recently, Callum said, when the Lions club arranged to have the names of the deceased added to a memorial erected decades earlier.
"I talked to a friend of mine who's also in the [masonry] business in Taupo and we got together and we did it for them at an extremely reduced cost… and it's just gone from there."
The project prompted his dad to open up about that fateful evening.
"He's told me more in the depths of what he had seen and so forth, which, you know, you can't put out on radio."
[h] 'This is supposed to be a happy time'
Callum and John were the first people journalist Hamish Williams interviewed for Tangiwai: A Forgotten History.
"I was reasonably new to the story of Tangiwai," he told Summer Times. "I had first learned about it as a kid actually reading a book. There was a series about New Zealand's disasters and Tangiwai was one of them, and that was about the limit of my knowledge.
"And then when the series was commissioned by New Zealand On Air, obviously we went to work and John and Callum were the first two people that I met associated with it.
"And it's just amazing because we may know about this part of our history. We may know the tragic details, but to be welcomed into John's home and then to meet John and Callum and to really start to understand, the depth and the gravity of this piece of our history, I came away from that first meeting thinking 'holy hell, I've got my work cut out for me'."
One of the first things he realised was "just how little prominence Tangiwai has had in our collective memories and their history and the prominence that it, I feel it should occupy but doesn't".
"And so we really explored as to why that might be, and there was some interesting things that came up.
"I think the most obvious is that it is a tragedy. It's an incredible loss of life, even comparative to more recent disasters, you know, like a Christchurch earthquake, and I would look at that and say, 'Well, why is it that this has happened?'
"And I think the fact is that on Christmas Eve when we have these 151 people that never made it to their destinations and that being the natural anniversary of it, it's not something that we probably particularly want to remember at that time of year. This is supposed to be a happy time, a joyous time.
"And I also think too that the society in which New Zealand was in 1953, we were still very much in that 'stiff upper lip', you know, 'keep calm and carry on' type scenario. And so there was a degree of, we don't talk about this, we move on - and that that very much was a prevalent attitude."
Not only was the time of year perhaps instrumental in our collective 'forgetting', but the year it happened in.
"Just remember 1953 New Zealand - quick history lesson. It was a bit of a joyous year in New Zealand - Sir Edmund Hillary had conquered Everest, the Queen visited just two days prior to Tangiwai, the first-ever reigning monarch to set foot in New Zealand.
"We were on a bit of a high. New Zealand was this wonderful burgeoning, you know, country that was really starting to find its feet on the international stage and then this horrible thing happened. And so I think it's time for us, you know, on the 70th anniversary to look back at Tangiwai and then ask the bigger question, and what does it actually tell us about our history, and also more importantly about New Zealand?
"And the conclusion that we came to in the podcast is really that there is an uncomfortable truth about Aotearoa New Zealand, and it's that it's a reasonably dangerous place to live.
"We don't have big giant carnivorous animals that hunt us down, we don't have snakes - but we do have an environment which is incredibly volatile."