As one of 10 commercial diving schools in the world and the only one in New Zealand, Huntly's Subsea Training Centre can't keep up with demand.
The NZQA programme has 50 students in the five-month course every year. And there's a guaranteed job for every graduate.
Operations manager Mike Pascoe was a commercial diver for 12 years before taking on the Huntly facility.
"Huon and Tassal aquaculture in Australia would take every graduate if they could - but we try and keep some in New Zealand.
"The aquaculture [industry] is booming in New Zealand and Australia - we cannot [train] enough students to support the number of divers required."
Then there's construction.
"A lot of construction wharf builds and America's Cup - they are going to redevelop the waterfront, so they will employ a lot of divers to work on that.
But why Huntly, with no coastline in sight?
Ironically, it's a former Solid Energy open-pit mine. The rehabilitated mine is now Lake Puketirini, perfect for a dive school.
If Pascoe tried to run a school like his offshore, it would mean that poor weather days would hinder how much time students could spend on the water.
"The lake is 87 metres deep, which is really deep for an inland lake - being an old coal mine, it's perfect for what we want to do.
"We have two barges anchored up out on the lake and we lower a platform down to whatever depth we need for the day and divers go down from there. We start nice and shallow and as they go through the course, the deeper we get - right up to 50 metres."
Hamilton man JK Bell, 20, was at a crossroads in his family's glazing business. He liked what he heard from a friend about what the course offered and hasn't regretted the decision.
"I just want to work hard, work everywhere, go travelling. I'm not too sure on specialising - but keen to get into stuff like working on the pipelines offshore, the deeper stuff - that is a goal, as it is better pay," Bell said.
"It is mint, as you learn new s... every day."
Bell had no diving experience, but like most Kiwi kids, he'd mucked around the beach.
"You get a bit nervous at the start, especially as you dive deeper than 40 metres, but once you get used to it - it is mint, mean as," Bell said.
The school under its former owner lost a student, Luqmanulhakim Bin Moien, of Malaysia, who drowned during an assessment dive on the lake on April 28, 2014.
The dive school and supervisor on the day were both fined over the 24-year-old man's death, and the school was required to pay reparation to his family.
Pascoe said not only is the school now under different ownership, there are only two employees who remain from that time.
"There have been big changes. We have changed a lot of procedures, so it's a totally different ballgame now.
"There is always a risk. So what we do now is we take all the students to the pools and do all the training in a nice warm pool for a week before we get anywhere near the lake. And then it's baby steps all the way."