From Taupō to Port Waikato, Tua and Courtney Karalus' ​Deep Dive Division hope to rid the Waikato River of wrecks.

The commercial dive outfit whose clients include the Hamilton City Council, Environment Waikato and Waikato Tainui has a laser focus on ensuring the river's health is maintained in keeping with mātauranga Māori principles – a point of difference in the industry.

'There are agreements in place with council, iwi and the river authority that the health and wellbeing of the river ought to line up with the health and wellbeing of the community. Restoring the mauri, the spirit, of the awa (river) is very important.

Video: Deep Dive Division.

'Before the riparian planting and all that other good stuff is done you actually have to pull stuff out. It's like a living entity, and people do forget that,” Courtney says.

Cutting his teeth diving the Rena Wreck alongside former SAS and navy divers, Tua who has a degree in environmental science, started the company he runs with his wife in 2018.

Initially, very few local government agencies were keen to get on board with the project, Tua says, despite a statutory obligation to do so.

'It was three years of trying to get support and funding to get these vehicles out. It started by finding some vehicles while we were doing some maintenance work with a side and down scanner from our dive vessel ‘Under Pressure'.

'From that process three years ago, to getting support from Waikato Tainui initially, we went to all local government and regional council, and no one wanted to fund. Sure, everyone supports a good story, but nobody wanted to stump up the cash.”

With $50,000 worth of funding from Waikato Tainui to undertake exploratory fact-finding dives the iwi were the pair's first backer.

'Tainui knew the years of rejection we'd had, and they backed us to scan and that really enabled us to gather that footage to put together a case, like you might do as a lawyer,” Courtney says.

Recent funding enabled the company to salvage wrecks, mainly cars, from five popular swimming spots throughout Hamilton and Ngāruawāhia.

”We've had funding to do five key swimming spots (Hamilton Gardens, Wellington St Beach, Pukete Boat Ramp, Narrows Boat Ramp and Ngāruawāhia) where people mainly do their manus and bring their kids down.”

With the River Authority now squarely on board, the ultimate goal is to scour the entire river for wrecks, from source to sea, says Courtney.

”Really the end goal for us is doing the whole awa – from Taupō to Port Waikato”

Tua adds that ideally the tributaries would be cleared too.

'There's the Waipa known to have multiple vehicles and rubbish in there and carries a high sediment load as well, which makes it absolutely dark brown as it enters the Waikato.”

With ten vehicles salvaged and another eight to go in the five spots they've surveyed so far, there is still work to be done Tua says.

'We are thinking there are hundreds. The feedback we get online is ‘hey do think you can get these vehicles out here? There's ten over here. So much over here.' if you think about what people can see then what about all the others that are hidden?”

As mullet jump in the river behind him, Tua explains the nuts and bolts of diving in a river notorious for its swift currents and limited visibility. It's tricky business, but his six crew are consummate professionals.

'Of all the environments we dive in, this is definitely one of the most hazardous. Strong current, sometimes up to eight knots, enduring force... add to that low to nil visibility, floating debris, logs, animals, gaming machines, lime scooters flowing past – it makes for a very testing working environment.”

Keeping staff on permanently in an industry where the norm is to rely on contractors, helps to ensure a good rapport with clients, and a familiarity with the assets being worked on, says the couple.

'The key is the unique set of skills each one of these people bring to your team. It's so hard to A, get the qualification as a commercial diver and then all the other skills sets they bring to the team. You want to look after them. They don't want to be a contractor for the rest of their life.”

- Jonah Franke-Bowell/Stuff.