A spring-fed limestone waterhole in South Africa is home to plants not seen underwater anywhere else in the world.

A spring-fed limestone waterhole in South Africa is home to plants not seen underwater anywhere else in the world.

In the spring-fed waters of three basin-shaped ponds in south-eastern South Australia, the water is so clear that plants can grow up to two meters deep, something not seen anywhere else in the world, an expert says.

Ewens Ponds is located about 25 kilometers south of Mount Gambier, in a spring-fed limestone pit.

Even on a scorching hot day, the fresh water temperature in the ponds remains a constant 16 degrees Celsius, according to Department of Environment and Water district ranger Ross Anderson.

Ewens Ponds is located in a spring-fed limestone pit.(Supplier: Michele Rougeau)

“Because of the flow rate here, where the ponds are emptied and replaced with water every 16 hours, they never have a chance to warm up,” Anderson said.

“It’s not like the taps turn every 16 hours, but it takes 16 hours for the ponds to completely change their water from the spring flow.”

The environment provides goods for underwater plants

Mr Anderson said the clear water allowed light to travel to the bottom of the ponds and for plants to grow such as water ribbons and rush-like plants.

“A lot of these species don’t exist at this kind of depth anywhere else,” he said. “And because the water is so clear here, they can grow at a much greater depth than they do elsewhere.”

“In other places, these plants live on the surface in very shallow water or even in areas where there is no water.”


The ecosystem supports a range of unique species, including the Ewens dwarf perch, which is exclusive to the area.

Mr Anderson said the pure, filtered water was also very old.

Underwater flowing plant.

Some of the plants found at Ewens Ponds while submerged in water cannot be grown anywhere else in the world.(Supplier: Michele Rougeau)

“It depends a little bit on where the springs come from within the ponds themselves, but this water is filtered through the limestone before it ends up here in the region of 30 or 40 years,” he added.

The changing landscape

Many of the areas surrounding Ewens Ponds were once wetlands just decades ago, Mr Anderson said.

Uncle Ken Jones, a traditional elder of Boadick County, was invited to help re-wet certain areas, similar to a program he participated in in the early 2000s.

“It worked well during the two years of trial, and we are looking forward to doing it again in other areas,” he said.

“Just raising the water table by a few hundred millimeters could mean we can rehydrate our amazing wetlands.”

Green plants on the ground in the pond.

The water temperature at Ewens Ponds is always 16 degrees with new water flowing every 16 hours.(Supplier: Michele Rougeau)

Uncle Ken said wetlands are important in preserving animals that swim in and out of the nearby ocean.

“Geese, stickleback crayfish… almost all of those animals have been lost, so what a great opportunity to partner to get some help with like-minded volunteers and land managers,” he said.

“We can turn it around a bit and save some valuable gems.”

Ewens Ponds is open to the public for diving and snorkeling. It is recommended to wear a wetsuit.

A permit is required, with reservations available through the state’s National Parks and Wildlife website.

    (tags for translation)Diving in Owens Ponds

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