There's concern for Fiordland's fish stocks and ecosystems as scientists and locals work to better understand how climate change is affecting the marine environment.
The project is a unique collaboration between local tourism companies and Victoria University researchers.
Even this remote corner of the earth, with its ice-carved fiords and towering mountain peaks, can't escape climate change.
"We've seen fish numbers slowly reduce. I've been diving in areas that've been lush and abundant looking and gone back for dives and it's different, dusty and dry," Southern Fiordland Initiative's Katherine Mitchell said.
To determine a baseline of data for measuring change, Mitchell helped set up the Southern Fiordland Initiative about two years ago after millions of sponges were bleached and killed in consecutive marine heatwaves.
"It was a massive deal, and it was kind of frustrating because clearly something big is happening here," she said.
Her group is working with scientists from Victoria University to monitor long-term changes in Fiordland, because although there's research showing the warming of shallower waters - they are in the dark about what's happening in the deep.
One of the tools is a CTD instrument which measures conductivity, temperature and depth. It's dropped into the ocean and dragged back up, gathering information on its way.
Victoria University marine biologist Professor James Bell said all the data from Fiordland will be incredibly valuable as we continue to see increases in temperature, as it provides an important baseline against which to compare change.
"Some of the bigger worries for us is changing climates. We know the earth is getting warmer, the oceans are getting slowly more acidic - it's those factors, particularly the temperature, that we're worried about," Prof Bell said.
They're going deeper than anyone has ever ventured before, using an underwater drone funded by the George Mason Charitable Trust to discover what lives in the deep.
"Fiordland is particularly unique because most of the environments here are below 30 metres, rocky faces that go down hundreds of metres," he said.
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Despite the deeper habitats being so common in Fiordland, there is little known about them and the Victoria University work is providing the first-ever high-quality video and images from the deeper water habitats. It'll help determine what's 'normal', and what isn't.
"And if we see something really different that might give us cause for concern and might then trigger further study in looking at what's caused that big change," Prof Bell said.
Keeping a close eye on it all is the Department of Conservation's (DoC) senior ranger Richard Kinsey. He's been working in Fiordland for 15 years and is keen to see more scientific research.
"The fiords are probably less well-studied than somewhere like Antarctica, so from a point of view of getting that baseline data - it's really important for us," he said.
He believes DoC's biggest concern is the fish stocks.
"For recreationally important fish like blue cod, there's been a reasonably obvious decline in my time since I've been here," Kinsey said.
"We should be assessing the way that we fish, what we take out of the ecosystem, and what we give back to it," Mitchell added.
The monitoring project started in Doubtful Sound, and through a collaboration with citizen scientists it's now moved south to Breaksea and Dusky sounds as well.
Because it's so isolated, the project relies on Katherine and Paul Mitchell using their charter boat, the Pembroke, for research.
The couple have several underwater and above-water temperature loggers in Breaksea and Dusky Sounds, as well as regularly using a CTD and logging the data.
"By doing that all the time we'll slowly be able to build up a picture - it's just that consistency of being there all the time. The data we are collecting we want it to be available for everyone researching in that area," Katherine said.
The data will build a clearer picture of the environment there.
"If we don't draw a line in the sand now and understand what ecosystem looks like, how are we going to quantify change as we move forward," she said.
