Defence Minister Jonathan Coleman said a briefing has shown the death of a soldier during a training exercise last year was preventable and some hard lessons will have to be learned.
Private Michael Ross fell from an inflatable boat into Moawhango lake near Waiouru in September last year and Navy divers found his body a week later.
The Sunday Star-Times has reported that an internal defence force investigation, which is not public, has found several safety failures led to Private Ross's death, including a lifejacket that failed to inflate.
The Labour Party is calling for a safety investigation covering whether there is a culture of taking short cuts in the Defence Force.
The party's defence spokesperson Phil Goff said the fatality was completely avoidable, and is the fifth non-combat death of Defence Force personnel in the past two years.
Mr Coleman told Radio New Zealand's Morning Report programme his initial briefing indicates the death was "entirely preventable" but several inquiries are continuing and he will not speculate on the cause of the accident.
Former Chief of Army Lou Gardiner says there is a clear procedure that a canister that had been used to inflate a lifejacket must be marked as unuseable and this did not happen.
A former squadron leader Rob Stockley has told Nine to Noon the Defence Force has a "can do" culture and a tradition of getting things done even if the risks are high. "When it comes to safety, that No. 8 wire approach doesn't do them justice."
Mr Stockley, now retired, leaked information on the fatal Air Force helicopter crash on Anzac Day 2010 and claimed it was connected with a culture of risk taking by Air Force crews.
The Defence Force has confirmed an inquiry into Private Ross's death is under way and says it will make any necessary improvements to its operations following the outcome of the investigation.
It says the investigation is nearly complete and has specifically looked at the lifejacket the soldier was wearing, as well as other systems and processes.