But below the surface, Victoria University of Wellington marine biologist Prof James Bell said it was a "completely different world".
"The terrestrial environment's got lots of cool things that people travelling across the water in Fiordland, perhaps wouldn't appreciate — all that amazing biodiversity that's under the water."
Researchers from the university are working with Environment Southland to develop the first comprehensive classification of the different habitats in the Te Moana o Atawhenua Fiordland Marine Area, which includes 14 fiords and 10 marine reserves.
Prof Bell said the Environment Southland-funded research aimed to help support evidence-based management of the unique environment.
"The aim of this project is to describe the distribution of different marine communities throughout Fiordland so, in the future, we can precisely map where they occur."
The research team had already spent several weeks diving on rocky reefs and soft sediments on the seafloor in Fiordland’s Breaksea Sound and Dusky Sound, to collect data on the marine communities living there.
"Many locations we surveyed had a high diversity of species, while others had very different and very low diversity.
"At one site, near Entry Island in Breaksea Sound, we found diverse communities of ascidians, bryozoans and sponges living on rocky reefs.
"In contrast, neighbouring soft sediment areas of the seafloor had comparatively few species.
"It’s important to capture these extremes," he said.
The researchers dived to depths of about 30m, taking high-resolution videos in the sounds, which were later analysed to classify the different communities found.
He said they were also using a remotely operated vehicle (ROV), which could dive to more than 100m.
"It's all in real time, so you never know what you're going to see," he said.
"Sometimes a shark might come past or you just enter a big school of fish or you see kingfish turn up — there's all sorts of cool stuff.
"And you kind of get out into the dark and then all of a sudden you'll see the clip will come up and there might be large black corals or I guess species that probably haven't been described before.
"There’s also lots of cool Nudibranchs — sea slugs — and there's things like seahorses.
"We’re finding super cool things as we’re doing our surveys."
While they did not have equipment capable of reaching the bottom of the deeper sounds in Fiordland, he was hopeful it would be possible in the future.
"It's probably just too dark or too far away from the food for there to be much life.
"But it would be interesting to know if anything is there.
"Eventually, we hope to have a complete picture of the different habitats in the entire Fiordland Marine Area, as well as the rest of Southland’s coastal marine area."
Environment Southland aquatic ecosystems team leader Ash Rabel said cataloguing the communities and their composition in this way provided a strong foundation for future scientific endeavour and supported evidence-based management of these ecosystems.
Reports from the research are available on Environment Southland’s website.
