In late-2024, a submerged mystery in the Bay of Plenty’s seabed resurfaced when a hydrographic survey uncovered a long-forgotten digger, still upright and undisturbed after more than 15 years. The near-new 12-tonne digger had fallen off a barge during transport from the Kaituna River mouth to Mōtītī Island.

Its rediscovery came as part of a survey to update nautical charts and improve maritime safety, drawing attention to both the digger’s surprising endurance and the technology that brought it back into the spotlight.

The discovery was part of a hydrographic survey led by Discovery Marine Ltd, using multi-beam echosounder technology to map the seafloor.

Conducted by Toitū Te Whenua Land Information New Zealand, known as Linz, the survey revealed high-resolution images showing the digger still sitting upright at 12 metres depth, with its top just 8 metres below the surface. These findings highlighted the importance of surveying the seafloor to ensure that nautical charts remained accurate and up-to-date for mariners.

Underwater in 2012

For Shane Wasik, a commercial diver and underwater photographer now based in Scotland, the rediscovery brought back memories of his own dive on the wreck. Wasik had first explored the digger with his diving buddy Graeme in 2012. Having heard rumours about the missing digger from fellow divers, the two set out to find it – eager to log the unique dive.

“We were both super keen to check it out. It was a one-of-a-kind wreck dive that we knew we had to experience,” Wasik said. “It was a ‘must-have’ for our logbooks.”

The location of the digger, which had fallen off the barge about six or seven years before, had been discussed in the local diving community.

The digger sitting upright on the seafloor. Photo/ Shane Wasik

In the winter of 2012, with ideal conditions – a crisp, clear day and light winds – they decided to investigate. The wreck was located between the Kaituna River and Wairere Bay on Mōtītī, an area often clouded by silt from the river’s sediment. Wasik and Graeme knew they’d have to be careful to avoid disturbing the silt and further reducing visibility.

“The river brings out a good bit of sediment. The wreck lies in an area which can be quite silty. We had to get quite close to see it properly and be very careful with our buoyancy to not disturb too much silt.”

Untouched

As the divers approached the wreck, Wasik, who has dived thousands of times, was struck by its condition. The digger was sitting upright on the seabed, seemingly untouched.

“There are many places where things are placed on the seabed for divers to explore, such as all the wrecks around New Zealand. However, I’d never seen anything like this.

“Everything looked as it would be normally with the control sticks all sitting in place. The arm and bucket sat on the seabed, just like someone had parked it up there intentionally.”

The structure had become home to marine life. Wasik saw schools of fish, a few small crayfish, and a John Dory swimming around the wreck. Over time, the digger had transformed into an artificial reef, with sponges, anemones, and mussels growing on it.

A close-up of the digger which has sponges, anemones, and mussels growing on it. Photo/Shane Wasik

Capturing the scene on camera proved challenging. The low visibility and light conditions made photography difficult, but Wasik got some close-ups, then used long exposures and a tripod to try to capture the full scale of the wreck.

“I was using a wide-angle lens and past the edge of visibility that I could only just make out the shadow of the structure.”

For years after, the digger remained on the seafloor, largely forgotten. Its retrieval was deemed too expensive to justify, so it continued to serve as a fish aggregating device for marine life.

Rediscovered

Then, in November 2024, the digger was rediscovered during the hydrographic survey. As the survey vessel MV Tranquil Image mapped the seafloor, the echosounder technology revealed the digger’s stable position. Annette Wilkinson, senior hydrographic surveyor at Linz, said that the discovery highlighted the importance of maintaining accurate nautical charts.

“While the digger may not pose an immediate risk, its rediscovery underscores why it’s crucial to regularly survey the seafloor and update charts for mariners,” Wilkinson said.

“This work is essential for ensuring the safety of mariners who navigate these waters, whether they are local fishermen or large shipping vessels.”

The survey, which began in November 2024, is expected to continue this year. A second survey vessel, the Tupaia, is mapping the shallower waters off Ōpōtiki.

The survey not only helps with navigation but also contributes to scientific research on the coastline and marine ecosystems, including how they might respond to events like tsunamis, Wilkinson said.

Wasik, now running a wildlife tour business in Scotland, reflected on his connection to the Bay of Plenty and the digger.

“We really miss the Mount,” he said. “This time of year, I’m most jealous of the sunshine and warmth compared to the depths of a Scottish winter! We’re hoping to visit soon, though travelling with young kids isn’t easy or cheap.”