Deadly lure of a magical underworld

Agnes Milowka indulging in her beloved sport of cave-diving. Picture: Neil Vincent Source: Supplied

Divers from across the globe arrive in South Australia every year to explore its cold, dark and eerily silent labyrinth of interconnecting passages.

They marvel at ancient wonders in an environment as alien to most of us as Mars.

Tragically, sometimes they die.

The death of experienced diver Agnes Milowka in the depths of Tank Cave this week has put the fringe sport into the limelight.

A distinctly marginal pastime - there are just 800 accredited cave divers in Australia - the safety of cave diving has moved along in leaps and bounds since a spate of deaths in the 1970s.

Despite this, two people have lost their lives while diving in South Australia in the past year.

Although Ms Milowka's death has rocked the diving fraternity, they insist their sport is safe.

Experienced instructor Tim Featonby said a rigorous accreditation process, administered by the Cave Divers Association of Australia, ensured only the best prepared and most highly skilled divers could explore the likes of Tank Cave.

While accidents still happen, the danger was more perceived than real.

"It was dangerous back in the 1970s, but they were pioneering what they were doing," he said.

"We've learnt a lot since then, particularly in Australia where our standards are high. We've got a very good safety record.

"I think its a very safe sport.

"There's nothing with teeth down there except us.

"There's no currents in Australian caves, so you can leave equipment in stages to assist you to get out. The number of instances of fatalities we've had is remarkably low."

Cave diving is a sport that combines the traditional scuba-diving threat of drowning with the added danger of getting trapped or lost in caves deep underground and running out of air.

Then there's the silt.

While Mt Gambier might be famed for its crystal-clear water, the merest touch on the wall of a cave can cause a silt-out, reducing visibility to zero and causing a diver to become lost.

So divers always reel out a guide line to allow them to return to safety even when they can't see.

Regularly visited caves have permanent guide lines installed.

Divers also carry at least two extra torches in case the primary one fails. 

An avid cave diver with 14 years' experience, Mr Featonby describes the experience like looking through a window to the past.

"Its hard to explain," he said.

"Everyone just sees rocks, but once you get under there it really is beautiful.

"It's a buzz and a challenge, going somewhere that very few other people in the world ever have or will get to.

"It's surreal ... you're cruising through a window in time - there's a lot of stuff down there that's thousands to millions of years old.

"You find a lot of fossils.

"In Tank Cave in particular you find sea urchins and little bits of coral and very occasionally you might find a shark's tooth."

Divers must go through a lengthy process of guided dives and training before they are allowed to attempt Tank Cave.

Ms Milowka, one of the best diving talents in Australia, had explored and mapped Tank Cave many times.

Exploring and mapping caves was her lifelong passion.

"It is a phenomenal feeling to reach a place that no other human has ever seen before," her website says.

Mr Featonby said it took a huge amount of planning and training to attempt a dive at Tank Cave.

"Its just a spider web down there," he said. "Every five metres there's another couple of tunnels opening up.

"You have to be very accurate and particular in what you're doing down there to ensure that you go in the right direction and you come back.

"But at that level, before you're released into it, you should definitely be at a standard that you can navigate it quite comfortably."

The first cave dives took place in the late 1950s.

In the early days ocean divers would blunder about the underground systems using a single tank of gas and homemade underwater torches.

The peculiar risks of cave diving meant a series of tragedies was almost inevitable.

Between 1969 and 1973, in Australia alone 11 divers lost their lives in underwater caves.

A public outcry led to the formation of the Cave Diving Association of Australia.

The association set strict safety and training procedures and has since certified 4500 divers.

If you don't have a ticket from the CDAA you don't get to dive in SA caves.

Until March last year there had not been a cave-diving fatality in Mt Gambier in 30 years.

Then a highly experienced 52-year-old diver drowned at Kilsbys Sinkhole.

The coroner is yet to determine exactly what happened but news reports suggested he might have become entangled in a guide line or had an underlying medical condition.