Undersea cables are the lifelines of the internet, carrying over 90% of the UK's daily internet traffic and contributing £65 billion to the economy. However, these cables are currently described as 'naked' and 'incredibly vulnerable' to sabotage by foreign states, including Russia. In response, experts at BAE Systems, a leading UK defence firm, are developing advanced vibration-detecting sensors to protect these critical infrastructures. The technology, known as distributed acoustic sensing (DAS), uses optical fibres within the cables to detect the faintest vibrations near the seabed. This innovation could transform undersea cables into a continuous network of 'microphones,' capable of monitoring everything from environmental changes to the movement of ships and even marine life. DAS technology is already in use on land and has been tested in limited commercial applications underwater. BAE Systems is now looking to enhance its military applications, aiming to detect threats before they cause damage. According to Tim O'Neill, Subsea Intelligence lead at BAE Systems, the system could alert operators if an anchor drags near a cable, giving time to stop a vessel or deploy military assets to intercept it. The technology is currently in the experimental phase, with data from DAS sensors being processed by artificial intelligence and machine learning systems to improve detection accuracy. Defence analysts believe this new technology could be a game-changer in underwater security. Alessio Patalano, an expert in undersea infrastructure at King's College London, suggests that the data from these sensors will greatly improve the ability to defend and monitor vulnerable undersea cables. He explains that the sensors provide continuous and detailed information about the environment around the cables, making the seabed 'slightly more transparent' and helping military planners better understand where and how to operate. This improved visibility could also speed up the response to any interference, allowing quicker identification and resolution of issues. The challenge now lies not just in making the technology work, but in managing the vast amounts of data it produces. A single DAS unit can generate up to a petabyte of data per day—equivalent to streaming 57 years of high-definition video continuously. Tools are being developed to filter and highlight the most relevant signals, ensuring operators are alerted only to potential threats. While the Ministry of Defence has not yet commented on the project, the advancements in DAS technology could mark a significant step forward in securing the UK's undersea infrastructure against future threats.