The Massey High School student was among a group of five friends who got in trouble at the Cascade Falls in the Waitakere Ranges after a sudden downpour in the area on Saturday afternoon.
Pastor Turagaiviu, who was like a grandfather to Sosi and his siblings, said their family was rallying to support Sosi's mother and his two brothers. Sosi was the middle child.
Their father, Joe Turagaiviu, was also being supported by family in Australia, where he is contracted to work.
"Sosi's mother was saying that the only thing she knows was that he was going to [tenpin] bowling with a group of boys.
"She told me that if she knew he was going to the Waitakere Ranges, she wouldn't have let him go. She's always careful about where they go for trips.
"But on Saturday, she told me that Sosi asked if he can go with the boys to bowling. She let him go and told him: 'Don't forget to come and work'.''
It is not known whether the friends changed their plans or if they had gone bowling earlier in the day before deciding to go to the falls.
Pastor Turagaiviu said the family had arrived in New Zealand from Fiji when Sosi was 3 years old. They lived in North Shore for most of his life, before they moved to West Auckland just over a year ago.
He was proud of the young man Sosi had become - a staunch Christian who had good friends and who worked hard at KFC Westgate to save towards buying his own car.
"That was how clever and good this boy was, he was about to get his own car. He would've used it his first week at school.
"He was a very hard worker and always very good at keeping money and looking after his job. He had a lot of good friends.''
The family is due to meet tonight to discuss funeral arrangements. However, Pastor Turagaiviu admitted many of them were still finding it hard to believe what had happened.