There is no shortage of headlines about high-profile cable breaks, particularly around the Baltic Sea and Taiwan. But it's worth remembering that where there have been faults, there have also been repairs.
Cable Repair Has Evolved
Ingrained processes and contingency plans have been instrumental in recovering service on key subsea cable systems. Repairing cables is a core part of the process for a cable-dependent society. And we've gotten good at it.
Modern cable repair typically entails a repair ship that uses a specialized hook to snag a damaged cable from the ocean floor. Once the cable is hooked, it's slowly pulled up to the surface and onto the deck of the ship. Typically, the damaged portion of the cable is removed and replaced with a new section of spare cable carried on the repair vessel.
Some repairs are faster than others. Much depends on the location and availability of the global cable ship fleet. In this recent example, a cable break near Taiwan was detected in late January. A cable repair vessel arrived several weeks later and was back in service by early March.
You Don't Hear About Most Cable Faults
As of early 2025, we believe there are over 1.48 million kilometers of submarine cables in service worldwide. Although we don't often hear about them, cable faults are a common occurrence. According to the International Cable Protection Committee, there are roughly 200 repairs required annually.
There's a reason we rarely hear about these cable breaks. It's because most companies that use cables follow a “safety in numbers” approach to usage, spreading their networks' capacity over multiple cables. If one breaks, the network will run smoothly over other cables while service is restored on the damaged one.
Accidents involving fishing vessels and ships dragging anchors account for two-thirds of all cable faults.
Environmental factors also contribute to damage. Tonga, which has only one domestic submarine cable, is a prime example of why resiliency is crucial. The nation has been known to battle both earthquake and volcano-based outages.
Maintaining the World's Subsea Cables
A new report by TeleGeography and Infra-Analytics projects a 48% net increase in total cable kilometers to be deployed in the world's oceans by 2040, driven by rising bandwidth demands and the need for network redundancy and resilience.
However, by the same year, approximately two-thirds of cable maintenance ships will have reached the end of their service life, with about half of the global cable ship fleet also approaching this milestone.
Meeting the challenges of the rapidly expanding submarine cable ecosystem and an aging cable ship fleet will require an investment of roughly $3 billion to sustain current service levels and avoid repair delays. This would entail the acquisition of 15 replacement ships and five additional ships to serve the global subsea internet infrastructure.
➡️ Get The Future of Submarine Cable Maintenance report here.
Alan Mauldin
Alan Mauldin is a Research Director at TeleGeography. He manages the company’s infrastructure research group, focusing primarily on submarine cables, terrestrial networks, international Internet infrastructure, and bandwidth demand modeling. He also advises clients with due diligence analysis, feasibility studies, and business plan development for projects around the world. Alan speaks frequently about the global network industry at a wide range of conferences, including PTC, Submarine Networks World, and SubOptic.
