Elisa Tests DAS Technology for Subsea Cable Protection in Baltic Sea
Finnish operator Elisa has wrapped up testing of subsea cable monitoring technology using Distributed Acoustic Sensing (DAS), conducted together with the Finnish navy and border guard . The system is now being built into an automated service that can alert authorities and infrastructure owners in case of exceptional situations, such as the approach of a ship dragging an anchor .
Elisa has had its cables damaged in suspicious incidents in the Baltic Sea in the past, including a December 2025 incident where a ship dragging its anchor damaged one of the company's subsea cables . In one of the 2024 incidents, the cost of cable repairs was said to reach at least €60 million (US$70 million) .
The DAS technology analyzes changes caused by vibrations in the reflections of light passing through the optical fiber, effectively turning the cable into a sensor that can pick up acoustic signals in its vicinity .
