BT’s Derek Cassidy helps us dive deep into the world of subsea cables and explains how they’re managed and protected.
Approximately 99pc of the world’s internet traffic runs through subsea cables. These lines send data as pulses of light inside thin strands of wires, or optical fibres, within the cable.
The world’s first transatlantic cable, which sent its first telegram 166 years ago, started in Valentia Island off the coast of Co Kerry in Ireland.
Since then, hundreds more cables have connected countries all over the world. As of September 2024, that’s a whopping 532 in-service systems, with another 77 planned, according to TeleGeorgraphy.
But while the technology behind the cables is impressive, the fragility of these underwater cables cannot be understated.
Looking at this year alone, there have been widespread, lengthy internet outages across portions West and Central Africa, parts of East Africa and South Asia, and Tonga all because of damage to submarine cables.
So, what exactly are the challenges at play here and who is responsible for protecting these cables? To find out, we spoke to Derek Cassidy, a principal optical engineer, senior submarine cable technologist and programme manager at BT.
With more than two decades of experience in the area of submarine cable technology, Cassidy is an expert in the precarious nature of the internet that runs along our ocean floors.
“I have a passion about subsea systems, and this has led me to the historical aspect of the network. In 2011, I established the Irish Communications Research Group with likeminded academics and industry experts to try and protect, preserve and promote out communications heritage,” he told SiliconRepublic.com.
“I am also the technical lead for the Valentia Transatlantic Cable Foundation and the World Heritage bid and also curate the Valentia Cable Museum. I am also offering advice to the Government and military community regarding certain aspects of submarine cable connectivity, design and history.”
Geopolitical issues
There are many factors that affect the subsea cable infrastructure, such as the environment, fishing activities and human interaction with seabed.
While environmental changes such earthquakes, subsea canyons and shifting sands can all cause damage, marine activity such as fishing vessels, anchor drags and criminal sabotage can also cause issues.
However, Cassidy also highlighted geopolitical issues as a threat to the deployment of subsea cables. Often countries are forced to balance the economic value of bringing in more subsea cables against the negative effects of having too many in one place.
“Countries such as Ireland have come to the party way too late and have seen loss of data centre and subsea cable business due to the political will that is in direct conflict with Government policy and strategy etc,” he said. “However, in other areas where there is no conflict or political interference, then there will be a huge benefit.”
Outside of internal struggles about whether or not to continue adding cables, there are also tensions between countries that can cause problems.
In 2019 for example, US officials sought to block an undersea cable network between Los Angeles and Hong Kong amid concerns that the undersea cables could increase the risk that an industry insider could “disrupt or spy on internet traffic”.
And with the very nature of cables crossing through various jurisdictions, permissions from different countries can cause problems.
Who protects our subsea cables?
With so many different entities and countries involved, Cassidy explained where the responsibility lies when it comes to managing subsea cables. He said the United Nations Convention Law of the Sea (UNCLOS) allows for Ireland to extend its borders out into the Irish Sea, Celtic Sea and Atlantic Ocean, effectively increasing its territory exponentially.
However, under UNCLOS, the Irish Government must allow other countries access to the new exclusive economic zone (EEZ) – that is the area beyond and adjacent to the territorial sea.
Additionally, subsea cable operators must have the ability to cross the EEZ sea floor without any undue costs, except when they enter the 12-mile limit, then they are required to apply for permits.
When it comes to protecting them, Cassidy said that all operators laying subsea cables do so at their own risk.
“There is not entitlement on any national Government to protect subsea infrastructure. However, some countries have listed subsea cables as critical infrastructure and have actively instituted plans to protect these assets, however, this is costly and can only be achieved if you have the available ocean-going assets such as the US, France and the UK,” he said.
“Even if you have a licence and permit from the national Government, this only gives you the right to be on the seabed and have an access route to your cable station, along with repairing and maintaining the cable asset.”
And while hyperscalers such as Google have been investing billions in the creation of subsea cables around the world – including one in Japan earlier this year – they are not telecom operators and therefore cannot operate any external commercial telecom infrastructure.
However, Cassidy said the hyperscalers do deploy and technically transmit their data across the globe using their subsea assets. “They do this by collaborating with other subsea operators who help to design, install and operate the subsea cable on behalf of the hyperscaler,” he said.
“These partnerships offer an opportunity for the subsea cable operator to have access to a fibre pair, or two, across an ocean or sea allowing them to extend their service area at a huge, reduced cost as the hyperscaler will be putting up most of the funding.”
How operators protect cables
So, if the cable operators are responsible for maintaining and protecting the cables, how do they do it? Cassidy said mitigating a lot of the issues stars with a good marine survey on the routes, the sea floor and the activities undertaken there.
“That is why subsea cables never take straight lines and usually meander across the seabed avoiding obstacles such as wrecks, unstable sea floor, fishing ground and unsuitable landings such as ports, harbours, special areas of conservation and areas of human activity such as beaches.”
In addition, the cable design itself plays a factor in protection, such as cable armouring, which has several types depending on the needs.
Lightweight armour or unarmoured cable is used for deep-sea deployment, single armour is for areas where there is little or no human activity and the cable can be buried, with double armour, the cable can be buried and there is some human activity, triple armour is for where there is more human activity and the cable is either buried or laid on a good sea floor, and finally rock armour where the cable comes ashore.
“This rock armour is deployed as the shore end and is seen on many subsea cables,” said Cassidy. “However, there has been a few cables which were not properly surveyed, poorly installed and without the proper armouring, one such cable being deployed in the Irish Sea which needed reinstalling a couple of times due to bad installation, cable management and design.”
The future of subsea cable deployments is changing. According to Cassidy, hyperscalers are leading the charge as they need the connectivity to keep up the growth in user and consumer demand.
But another technology being incorporated into subsea cables is smart and environmental sensors that will enable subsea cables to add value to the normal deployment of cables.
“The geopolitical issues will always cause a problem and these need to be sorted,” said Cassidy. “Having little or no cable spatial divergence will cause future problems as issues will arise regarding spatial awareness and protected routes.”
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