He came across operational diving and it ticked all the boxes for him.
"It's something you have to be completely focused on doing. You have to switch off the cold and the pain - kick off at 5 in the morning on a Monday and knock off at 5 in the evening on Friday."
Part of nine trainees for the navy's elite Operational Divers Course, he excelled and at the end of the gruelling 16-week course late last month was one of the remaining three who made it through and qualified to become part of the 20-strong team.
His success came as no surprise to the officer in charge of the RNZN Dive School, Warrant Officer Lance Graham.
"He was the best all round recruit," WO Graham said.
"And he was a top student on the diving course - he's a high flyer."
WO Graham said the diving course was intentionally tough, mentally and physically, as the tasks the team were often called upon to carry out were at the top end of the tough scale. "It's about the drive and determination - they need to want to do it because from day one the pressure goes on," he said.
Trainees also had to be at the peak of fitness, and in that OD (Ordinary Diver) Leadbetter had a great start.
Before joining the navy 14 months ago he worked as a physical trainer in Napier and was a champion kickboxer.
The physical tests were the highest in the navy and he emerged with full marks.
"You can be down there for up to four hours. There's often nil visibility and it's very cold - it is a pretty harsh working environment," he said.
But he relished the challenges of everything from setting explosive charges to deepwater construction and demolition using specialist cutting gear.
Members of the dive team get called upon to work in many places, and next year OD Leadbetter is looking at deployments in the Solomon Islands and the United States.
It was the challenge and the career he had been searching for, he said, adding he would stay "as long as they want me". There was no doubt about that, WO Graham said, adding that in two months OD Leadbetter would rise to AD (Able Diver).
"He's got officer potential."