18 June 2025: For someone who lives as far from the sea as it’s possible to be in the UK, John Wrottesley has been obsessed by the ocean for almost his entire working life. The Midlands resident is the Executive Director of the European Subsea Cables Association (ESCA), the culmination of decades working on the planning and operations of what is arguably the world’s most underappreciated yet most critically important technology – subsea cables.

It’s a common misconception that satellites carry the world’s phone and internet traffic. It is in fact subsea cables that carry out this crucial role, ferrying vast quantities of data between continents. Subsea cables are not only essential to global communication, world trade and the internet as we know it, they’re also an integral part of Vodafone’s heritage. They’re also vital to Vodafone’s present and future. From the 2Africa cable which encircles that continent to connect dozens of countries. To the new VodafoneThree project investigating the feasibility of building a new subsea cable to connect the Shetland Islands to the mainland UK.

Build it and they will come

As the world’s usage of the internet and telephony continues to grow exponentially according to John Wrottesley and ESCA – with an estimated 40% year-on-year increase in demand – so does the need for subsea cables, either entirely new ones or upgrades to existing cables. Organisations like ESCA engage with governments and communities around the world so that subsea cables can be built and then protected.

While the need to meet that 40% growth in demand for connectivity is important, John urged us all to look beyond the number: “That doesn’t mean we’re looking at 40% more cables every year, but it does mean that we need newer, higher-capacity cables and also diverse routing. So, if we want cables to be secure and resilient, they need to have geographically diverse routing. If you have damaged cables, traffic is rerouted in the blink of an eye, so there is seldom disruption to communications.”

Then there’s the thorny topic of money: Building, laying and repairing subsea cables requires plenty of it. According to John, financing can be hard to come by for subsea cables serving some populations, such as far-flung island communities with small populations.

Creative solutions are needed. From multinational and multi-organisational efforts, such as the one that financed the 2Africa cable, to funding from institutions like the World Bank, especially when a compelling social value case can be made. Reusing retired cables from other routes, to connect underserved communities can be another possibility, although John notes that this won’t always be possible.

The perfect home for a subsea cable, according to John, is a flat and featureless seabed to minimise the chance of damage to the cable from rough weather hazards, such as underwater landslides and turbidity currents, as well as even more dramatic events such as underwater volcanic eruptions. These account for approximately 15-20% of all cable faults, annually, according to statistics from the ICPC (International Cable Protection Committee).

The seabed should also preferably have plenty of sandy sediment so that the armoured cable can be buried in it for extra protection. However, such underwater conditions are more sought after than ever for other infrastructure, from transnational power cables and renewable energy generation to carbon capture and storage, all which must be carefully routed around. Cable routing also has to take account of and protect the biodiversity of the marine environment.

Damage assessment and prevention

While a lot of media attention has focussed on the potential sabotage of subsea cables during a geopolitical conflict, John is keen to put such concerns into context: “Fishing, or ships’ anchors, remain the biggest cause of damage, accounting for around 70% of cable faults every year. They’re the primary cause of cable faults, between 150 and 200 global cable faults annually.”

According to John, preventing such accidental damage involves the confluence of high-tech mapping and old-fashioned leg work: “If you tell people where they are, disseminate that information well and make sure they’re aware of how to operate safely in the vicinity of cables, then they’re far less likely to damage them.

“Organisations around the world, such as ESCA, publish regional cable charts and hydrographic charts. This information can be put on a file that is fed into fishing plotters, so fishing boats know where the cables are and can stay away from them.”

For the fishing boat operators unaware of these maps, or are simply using plotters with outdated maps, John and ESCA have an old school outreach campaign. “We have dedicated fishing officers who go out on port tours to stand on the quay side and meet and inform fishermen who may not know about subsea cables or how to install the plotter file and so on. We hand out things like beanie hats, tape measures and mugs so that they have subsea cables at front of mind.”

ESCA’s outreach programme to fishing boats is representative of that crucial yet easily overlooked ingredient to successfully building and deploying subsea cables – the engagement and cooperation of the people affected by their presence and building good relationships. After all, while it’s easy to think of subsea cables as connecting continents and data centres, what they really connect is people with each other.