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

What happened

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.

Contributing factors

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.

Lessons learned

1. Anchor equipment failure on a tanker allowed dragging over roughly 100 km of seabed, so operators of subsea pipelines and cables must verify that burial depth and route protection can withstand prolonged anchor strikes.
2. A bulk carrier suspected of cable damage was in an exclusive economic zone rather than territorial waters, so operators should plan for delayed authority response and boardings in such zones.
3. Eleven submarine cables were damaged in the region over about fifteen months, so operators must treat anchor strikes from shipping as a recurring risk in route and spares planning.

More lessons on electrical protection and isolation, from every incident on the register.

Not yet known

• Exact cause of each incident
• Model and age of damaged cables and pipeline
• Duration of outages and repair costs
• Which coastal state detained the tanker

This entry is updated when these are reported. Get an alert for the next one like it.

Source

atlanticcouncil.org