The friends of two men who died during a night dive on Great Barrier Island say the pair was devoted to outdoor sports, and both had a lot of experience in the water.
They're now determined to find out exactly what went wrong, to prevent another tragedy.
They were mates brought together by a passion for spearfishing and freediving.
But the men are now missing one of their crew -- Igor Petrenko -- a 31-year-old from Ukraine who never surfaced after a night dive for crayfish.
"He is pretty much like my family -- I call his mum like my mum and it's just a shock for us all," says Igor's friend Pavel Kondakov.
Igor was not only a passionate outdoors man, he was a model and digital artist who in 2012 showcased his work promoting New Zealand in New York's Times Square.
His mates say he was a fearless adventurer, and they still don't have a clear picture of exactly why he couldn't get back to the surface.
"We need to know. The families need to know and the whole free diving and spearfishing community need to know what happened to prevent that from happening in the future," says Mr Petrenko's friend Arthur Sarandov.
There's been speculation that a current may have held him underneath the water or that he became entangled in seaweed.
What is known for sure is that another of his diving group, Gena Sibaev, dived in to try to save his buddy.
"There was panic on the boat and Gena was the one who said 'Stop, let's not panic, he's probably gone. Call 111 and I'll go and have a quick look'," says Mr Sibaev's friend Alex Scherbakov.
Alex Scherbakov says it was typical of Mr Sibaev to try and help -- it was in his nature.
"He put the gear on, take the weight belt and he was gone and didn't surface.
"I feel a real privilege to know him and am so devastated he's not with us."
Mr Sibaev was a champion mountaineer and had lived in New Zealand since 2006.
And sadly it was that attraction to this paradise that claimed their lives.
Family wish to advise that a funeral for Mr Sibaev will be held on Sunday at 12:30pm at the North Harbour Chapel on 185 Schnapper Rock Rd in Albany.
Newshub.
