The CSIRO mapping showcases a stunning visual of the lake’s true depth, offering insights that were previously unseen. The deepest section of the lake is located in its southern region on the western side, tucked away in a corner. “It’s towards the south on the western side, just in the corner, basically,” an expert explained, hinting at the powerful natural forces at play. “We can almost see the glacier would have really grinded through that corner,” he added, highlighting the geological history etched into the lake’s depths.

This remarkable discovery was made possible through advanced technology. A multi-beam device was mounted onto the CSIRO vessel RV South Cape, which traversed the lake, using pulses of sound to meticulously measure the water’s depth. This sophisticated method has unveiled a view of the lake never seen before, providing a deeper understanding of its underwater landscape.

Underwater landscape revealed

A multi-beam was mounted onto CSIRO vessel RV South Cape as it travelled up and down the lake, using pulses of sound to measure the water depth, revealing a view of the lake never seen before.

CSIRO hydrographic surveyor Augustin Déplante was part of the nine-day expedition. Source: SBS News / Kerrin Thomas

“Seeing the sharp cliffs on the edges of the lake, we can clearly see some areas that have been carved by the glacier,” Déplante said.

“It can go really shallow into regions, less than less than two meters, even less than a meter as well as long as there’s no hidden rocks or anything underneath the surface,” CSIRO research engineer, Dr Hui Sheng Lim, said.

Dr Hui Sheng Lim was among the CSIRO researchers who mapped the lake. Source: SBS News / Kerrin Thomas

“So those are the areas where the big vessel won’t be able to get to.”

“You can see a meter here, and then next moment you are in a 10-metre zone, and next moment you’re already 30 metres, 50 metres deep.”

The area is known for its strong winds and unpredictable weather. Source: SBS News / Kerrin Thomas

Otter can also operate autonomously, following a precise, pre-planned path.

“One of the most useful features is we will be able to autonomously find gaps and find the best way to cover those missing gaps in our data sets,” he said.

‘Most peaceful place on this planet’

One of Michael Croghan’s most prized possessions is a bottle of gin lowered to the bottom of the lake. Source: SBS News / Kerrin Thomas

One of his prized possessions is a bottle of gin a team of researchers lowered to the bottom of the lake a few years ago.

“It’s now been depth tested I think that was to about 120 metres,” he said.

Snow, wind and swell

“Being on a small boat, like South Cape, sometimes I felt like I was in the Southern Ocean, basically.”

The team encountered snow, big swells and blustery winds as they conducted their research. Source: SBS News / Kerrin Thomas

The detailed data collected will be made public, providing an important resource, it’s hoped will fuel further study of Lake St Clair.