Submarine cables are undersea fiber-optic links that carry most international internet, voice, and cloud traffic between countries and continents. They are not just long strands of fiber: each system also depends on landing stations, power feed equipment, branching units, and network management systems that control traffic and restoration. Because of that, the security of a cable system includes both physical protection and cyber protection.
In cyber security, submarine cables matter because attacks can target the weak points around the cable rather than the glass in the sea. Threats include sabotage, tapping, service disruption at landing stations, and compromise of management interfaces used for provisioning or monitoring. Defenders reduce risk with route diversity, hardened landing sites, strict access control, segmentation, logging, and fast repair and recovery plans. In practice, a cable can be physically intact yet still be disrupted if its control plane, approvals, or operational access are compromised.