The Coroner has released the findings into the death of 16-year-old, Tarawera High School student Ethan Fitzpatrick.
The New Zealand Herald reports, Fitzpatrick drowned at Lake Rotomā, while on a snorkeling trip in March 2020.
He was practicing duck-diving with a paired buddy and was unobserved for 15 to 25 seconds.
Coroner Matthew Bates said, Fitzpatrick then got into difficulty, inhaled water and became unresponsive.
Fitzpatrick was taken out of the water and efforts to revive got underway and lasted up to an hour
However, Fitzpatrick never regained consciousness and died at the scene.
A Worksafe investigation found the school had inadequate emergency planning and supervision.
Bates said, a teacher drove half a kilometer to ring 111, due to unreliable phone service in the area.
But he said, there's no evidence to determine if immediate communication would have changed Fitzpatrick's outcome.
It recommends, an open-water recreational snorkeling code, similar to one used in Queensland be developed here.
Bates has also called for easy access to a defibrillator at education outside of the classroom activities.
Image: Wikipedia