Damage to Balticconnector pipeline and Baltic Sea subsea cables, 2023-2024

During 2023 and 2024 a series of damage incidents affected submarine cables and a subsea gas pipeline in the Baltic Sea and Gulf of Finland, in the waters of Finland, Estonia, Sweden, Lithuania, Latvia, Germany and Denmark, drawing sustained attention from energy security authorities. In October 2023 the Balticconnector gas pipeline and two telecommunications cables were damaged. The investigation reported that a container vessel had dragged its anchor across the seabed, and the vessel's operator acknowledged the damage and described it as accidental. In November 2024 two submarine data cables linking countries on opposite sides of the sea, including the Finland to Germany C-Lion1 cable, were damaged, and a bulk carrier was identified as a vessel of interest. The vessel was within an exclusive economic zone rather than territorial waters, which complicated boarding by national authorities. In December 2024 a submarine high voltage direct current power interconnector in the Gulf of Finland and several telecommunications cables, including a Sweden to Lithuania cable and a Sweden to Latvia cable, were damaged. A tanker was detained by the authorities of one coastal state, and investigators reported that ship records indicated anchor equipment failure consistent with anchor dragging over roughly 100 km of seabed. Public reporting states that eleven submarine cables were damaged in the region over about fifteen months. In response, coastal states and an international security alliance increased naval patrols and surveillance in the area from early 2025. Later reporting noted an emerging view among some western intelligence services that several of the incidents were likely maritime accidents involving poorly maintained vessels rather than coordinated sabotage, although attribution remains contested in the policy and academic literature.

Drawn from published policy and academic analysis of the pattern rather than from any single investigation: (1) high shipping density in narrow waterways crossing multiple subsea cable corridors, so exposure to anchor strikes is a function of traffic volume and routing; (2) anchor equipment failure on poorly maintained vessels, where windlass or brake failures can cause an unintended anchor drop and dragging can continue for a substantial distance before the crew detects it; (3) legal ambiguity over the authority of coastal states to board vessels suspected of causing cable damage while those vessels are in exclusive economic zones rather than territorial waters, together with differing adoption of the relevant international conventions between flag states; (4) variation in burial depth and route protection between cable assets, with older assets generally reported to have less protection than more recent installations; (5) growth in the density of subsea assets, so that shipping patterns which previously produced rare damage events now produce them more frequently; (6) attribution between deliberate interference and accidental damage remains contested, with public evidence cited in support of both interpretations at different times.

1. Treat damage from maritime traffic as a recurring operational risk for submarine cables rather than a remote contingency, and reflect it in outage risk assessments and spares planning.
2. Run periodic burial depth and route protection surveys that address both as laid burial integrity and its degradation over the operating life, and record findings against the original burial specification.
3. Secure access to cable repair vessels in advance through contract or a standing arrangement with regional repair operators, rather than seeking capacity after a fault.
4. Plan for repair timelines measured in weeks to months, covering fault location, vessel mobilisation, weather windows and recommissioning, and test system adequacy and commercial exposure against an extended outage.
5. Assess the wider system consequences of losing an interconnector, including frequency response and reserve requirements, and confirm that fast acting response resources are sufficient for the loss of the largest infeed.
6. Share cable route data and traffic monitoring information with national maritime authorities and with cross sector forums covering telecommunications, power and gas assets sharing the same corridors.
7. Track developing regulatory requirements for subsea infrastructure protection and reflect them in inspection, reporting and route surveillance arrangements.
8. Maintain a documented cable fault contingency plan, including notification routes to maritime and security authorities, and rehearse its activation on fault detection.

atlanticcouncil.org/in-depth-research-reports/issue-brief/how-the-baltic-sea...