More than 1m kilometres of cables snake along the world’s ocean floor, ferrying data between distant lands. Fibre-optic filaments whisk emails, Netflix and military secrets through deep water, where the cord – about as thick as a garden hose – gathers barnacles and seaweed.
Australia is connected to 15 of them (that we know of), with the main landing stations in Sydney and Perth. They are buried under the beach, then fed out into the open water at depths of up to 8km before re-emerging in landing stations in Singapore, Oman and Hawaii, among others.
And they’re vulnerable to sabotage and accidents, to hacking and (very occasionally) sharks.
Last month two cables in the Baltic Sea – one connecting Finland and Germany, the other connecting Sweden and Lithuania – were damaged in a suspected sabotage attack.
They were damaged at about the same time a Chinese-registered ship passed over them.
On Thursday the Swedish prime minister, Ulf Kristersson, said the Baltic Sea was now a “high-risk” zone.
And experts say Australia’s own cables are not immune from threats.
Despite the blustering promises of satellite technology, and despite the difficulty of building infrastructure thousands of metres beneath the surface, these cables still carry 99% of Australia’s data.
They can carry up to 300 terabits of data a second, making their capacity “virtually limitless”.
The maritime security expert Sam Bashfield is a research fellow at the University of Melbourne’s Australia India Institute.
He says satellites are critical for remote areas, war zones and some backup, but the “backbone” of the internet are cables.
“We see this huge increase in demand for bandwidth … even though we see satellite technology improving,” he says. “The global demand for data is also increasing at this crazy rate, so it still requires these submarine cables.
“Elon Musk’s Starlink gets a lot of media headlines [but] the big issue is that cable remains the backbone of global data transfer. It’s so much faster, it’s so much cheaper and the capacity is just so much higher.”
If Australia was cut off entirely from those cables, essential services would be disrupted and there would be political, military and economic ramifications – digital technology contributes $167bn to the economy each year.
“Without them, the internet as we know it would cease to exist,” Cynthia Mehboob, who is doing her PhD on the politics of undersea cables, says.
Mehboob, who is in the Australian National University’s international relations department, says Australia’s reliance on the cables will only grow.
“They’re vital for defence, for sharing intelligence,” she says. “Our Five Eyes arrangement is reliant on subsea cables.
“Disrupting these cables would have a very serious geopolitical impact on Australian security.”
In 2014 Google announced it was reinforcing cables with a Kevlar-like substance after a series of shark bites. A widely shared video showed a shark wrapping its teeth around a cable briefly before swimming off.
But that’s not the biggest threat. Bashfield says fish bites are only responsible for 0.1% of damage.
It’s fishing incidents that are far more common. Dredging, nets and trawlers can do damage, and anchors dragged over the cables can destroy them. Then there are geological events, such as underwater landslides or volcanoes.
“That’s the unintentional damage,” he says. “Then you get into statecraft … the intentional stuff, this cutting of cables, they’re intentionally sabotaged as an act of war or in a grey zone conflict.”
There are “choke points”, Bashfield says, where the cables hit the landing stations and all that data is flooding through. They are the potential sites for espionage and siphoning data for intelligence, he says.
Mehboob says a “black swan” event, such as all the cables being cut at once, was “incredibly unlikely” but not impossible.
“If it happened, it would be a catastrophe,” she says, adding that repairs could take weeks.
There are between 100 and 200 breaks a year but only a limited number of ships that can fix them.
When two of the three cables connecting Tasmania to the mainland were accidentally cut on the same day in March 2022, it gave an idea of the disruption that occur. Tonga, which has only one cable connecting it to the rest of the world, spent weeks without the internet this year.
Last week Google Cloud revealed its Australia Connect project. New cables will connect Australia with Christmas Island and Fiji, where other connections go on to Singapore and the US.
The communications minister, Michelle Rowland, said the new systems would “expand and strengthen the resilience of Australia’s own digital connectivity” and “support secure, resilient and reliable connectivity across the Pacific”.
Australia has also announced it will spend $18m over four years on a cable connectivity and resilience centre to strengthen engagement in the region – a move broadly seen as part of the Quad’s efforts to limit China’s influence.
But it doesn’t own the cables – they’re owned by telecommunications companies and increasingly the “hyperscalers”, including Amazon, Meta and Google.
Meanwhile, the geopolitics involving Australia, China, Taiwan and the Pacific remain complicated.
Mehboob says while Australia has cable protection zones, even flagging them makes it clear to potential bad actors exactly where the cables are. And there’s no easy way to work out if damage has been done intentionally.
“It’s a tricky attribution space,” she says. “Identifying intentional sabotage on the sea bed has always been a challenge.
“It makes things a lot more murky.”
