Estonian Subsea Cable Landscape: Outages, Resiliency & Sabotage Suspicions - Part 1

Estonia is a small Baltic nation with 1.4 million inhabitants. It has eight subsea fibre optic cables plus several power interconnectors. It is a large number given its land mass and population. Over the last several years Baltic Sea outages have been frequent with many in the Nordics pointing their finger at Russia. Many of these outages have involved cables landing in Estonia.

However, the Baltic Sea is extremely shallow. Its average depth is 52 to 55 meters. So cables in these waters are extremely vulnerable to fishing vessels and cargo ships dragging anchors. If they are not buried deeply in protected sea lanes, damage is inevitable. The other factor is the Russia shadow fleet. Europe is weaning itself off Russian gas imports with the figure falling from 8 billion cubic meters per month in early 2022 to 2 billion cubic meters today. When the war began, sanctions forced European headquartered global shipping lines to either stop serving Russia or place restrictions on acceptable cargo. But shipping demand actually rose as Russia ramped up LNG exports and military production. As major shipping companies pulled out, a host of smaller companies with ships in poor condition and low quality crews took their place.

So there is no need for sabotage to explain 'the surge' in cable damage. First of all, we don't know there is a surge because there are no publicly available data sets on cable faults. But assume the surge is real. Then the most plausible explanation is increased St. Petersburg cargo traffic involving a third rate cargo ship fleet. Note that most of Estonia's cables are perpendicular to the flow of ships. So if a ship inadvertently drags in anchor in this area it is almost guaranteed to sever at least one, but more likely several cables. The chart below shows that some major shipping companies like MSC actually doubled their St. Petersburg business from 2021 to 2025. So there are probably more ships using its port relative to the pre-war period. At the same time, the shadow fleet consists of largely small time operators whose ships might need repairs of anchoring mechanisms and better crews. In fact, when the Finnish authorities seized the Eagle S. (it dragged its anchor and sliced through many cables), they found 32 safety violations. Items included broken navigation equipment, unreliable fire alarm system, fire pump failures, and the like.

Open issues include whether the Estonian cables are buried deep enough. My bet is that they are buried 1 to 1.5 meters deep when in fact they should buried from 2 to 3 meters. That is consistent with their advanced age. In fact, with the exception of E-FINEST, RFS in 2010, all these cables were installed between 1994 and 2000. The fibre optic cables have very little capacity and hence minor impact on Estonian telecommunications. This begs the question of why Russia would target old, low capacity infrastructure near the end of their operating life spans. Does it appear to be a smart strategy for spreading public panic.