It was the first days of 2022, after a massive volcanic eruption, when Tonga fell into darkness. The underwater eruption – 1,000 times more powerful than the bomb dropped on Hiroshima – sent tsunami waves across the nearby archipelago of Tonga, blanketing the island’s white coral sands in ash.
The force of the Hunga-Tonga-Hunga-Ha’apai eruption cut off the internet connection to Tonga, causing a communications blackout at the time the crisis arose.
When the undersea cable that carries the country’s internet was restored weeks later, the scale of the disruption was clear. The lack of connectivity had hampered recovery efforts while devastating businesses and local finances, many of which rely on remittances from abroad.
The disaster exposed the extreme vulnerability of the infrastructure that supports the Internet.
Contemporary life is inextricably linked to an operational internet, says Nicole Starosielski, a professor at the University of California, Berkeley and author of The Undersea Network.
In this sense, it is similar to drinking water – a utility that sustains our existence. And like water, few people understand what it takes to transport it from a distant reservoir to our kitchen taps.
Modern consumers have come to think of the Internet as something invisible in the atmosphere—an invisible “cloud” just above our heads, raining data down on us. Because our devices aren’t tethered to cables, many of us think the whole thing is wireless, Starosielski says, but the reality is far more extraordinary.
Virtually all internet traffic—including Zoom calls, movie streams, emails, and social media feeds—reaches us via superfast fiber-optic cables laid on the ocean floor. These are the arteries of the modern world, stretching nearly 1.5 million kilometers beneath the sea, connecting countries with physical cables that carry the internet through them.
Starosielski explains via WhatsApp that the data her voice transmits goes from her mobile phone to a nearby cell tower. “That’s basically the only wireless hop in the whole system,” she says.
From the transmitter tower, it travels along a set of terrestrial fiber optic cables, which travel underground at the speed of light. It then travels to a cable landing station—usually somewhere near water—and from there to the bottom of the sea, before emerging again at a cable landing station in Australia, from where the Guardian speaks to Starosielski.
“Our voices are literally at the bottom of the ocean,” she says.
Spies, sabotage and sharks
The fact that the data that powers communications for financial institutions, governments and some militaries travels through cables no thicker than a garden hose and with little protection from the seawater above has become a cause for concern for lawmakers around the world in recent years.
In 2017, NATO officials reported that Russian submarines had stepped up their surveillance of internet cables in the North Atlantic, and in 2018 the Trump administration imposed sanctions on a Russian company that had reportedly supplied Moscow with “underwater capabilities” aimed at monitoring the underwater network.
A Russian attack on undersea cables would “cause significant damage to our economy and our daily lives,” said Jim Langevin, then a member of the U.S. Armed Services Committee.
Targeting internet cables is a weapon Russia has long had in its hybrid warfare arsenal. When Russia annexed Crimea in 2014, Moscow severed the peninsula’s main cable link, giving it control of the internet infrastructure, allowing the Kremlin to spread disinformation.
Global conflicts have also been shown to have unintended, disruptive effects on internet cable systems. In February, Iran-backed Houthi militants attacked a cargo ship in the Red Sea. The eventual sinking of the Rubymar was likely responsible for severing three undersea cables in the region, disrupting a significant portion of internet traffic between Asia and Europe.
The U.S. and its allies have also expressed serious concerns that adversaries could tap into the undersea cables to obtain “personal information, data, and communications.” A 2022 congressional report on the issue highlighted the increased potential for Russia or China to gain access to the undersea cable systems.
It’s a method of espionage the US is all too familiar with: In 2013, The Guardian revealed that Britain’s GCHQ had tapped into the internet’s network of cables to gain access to vast amounts of communications between completely innocent people, as well as potential suspects. This information was then passed on to the NSA.
The documents, made public by whistleblower Edward Snowden, also reveal that an undersea cable connecting Australia and New Zealand to the US was tapped to give the NSA access to internet data from Australia and New Zealand.
Despite the many dangers and increasingly loud warnings from Western governments, calls for more action to secure the cable network remain largely unanswered, and many believe the threats are exaggerated.
“There are no publicly available and verified reports indicating intentional attacks on the cable network by any actor, be it Russia, China or a non-state group,” a 2022 EU report said.
“This implies that the threat scenarios discussed may be exaggerated.”
An expert who spoke to the Guardian was more blunt in his assessment, describing the threat of sabotage as “bullshit”.
The data confirms this, showing that sharks, anchors and fish pose a greater threat to the global Internet infrastructure than Russian spies. A US report on the subject found that the biggest threats to the network are “accidental incidents involving people”. On average, a cable is cut “every three days”.
“In 2017, an undersea telecommunications cable was accidentally cut by a ship off the coast of Somalia, causing a three-week internet outage that cost the country $10 million a day,” the report said.
An unequal internet
For many experts, however, the greatest dangers to the Internet are not sabotage, espionage or rogue presenters, but the uneven distribution of the cable infrastructure that runs across the globe and connects the world’s digital networks.
“There are not cables everywhere,” Starosielski says. “There is a concentration in the North Atlantic connecting the United States and Europe, but there are not as many in the South Atlantic.”
“So you see some parts of the world have a high degree of connectivity … and diversity in terms of having multiple routes in case there is a rupture.”
In 2023, there were more than 500 communications cables on the ocean floor. However, a quick glance at a map of the world’s submarine cable networks shows that they are largely located around economic and population centers.
The uneven distribution of cables is most apparent in the Pacific, where a place like Guam, with a population of just 170,000 and a U.S. naval base, has more than 10 internet cables connecting the island. New Zealand, with more than 5 million people, has seven. Tonga has only one.
After the 2022 Tonga eruption, governments around the world took action. They commissioned reports on vulnerabilities in existing submarine cable networks, while technology companies hardened their networks to ensure something like this would never happen again.
Last month, the internet in Tonga was down again.
Large parts of the country were left in the dark after the undersea internet cable that connects the islands’ networks was damaged, causing chaos for local businesses.
For now, the economic fundamentals are favorable for building more cables in the Western world and emerging markets, where digital demand is booming. Despite warnings of sabotage or accidental damage – experts say that without market pressure to create more resilient networks, the real risk is that places like Tonga will be left in the dark, threatening the promise of digital equality on which the internet is based.