Mysterious Break in Baltic Sea Data Cable Between Finland and Germany

The NATO flag (C) and Finland flags flutter over the building of the Ministry of Foreign Affairs in Helsinki, Finland, on April 4, 2023. Sergei Grits/AP Photo

A submarine data communications cable across the Baltic Sea between Finland and Germany has broken, and the cause for the disruption is being investigated.

On Nov. 18, “a fault” was detected in the C-Lion1 cable belonging to the Finnish state-controlled data services provider, Cinia, which runs nearly 1,200 kilometers (746 miles) from the Finnish capital, Helsinki, to the German port city of Rostock.

“Due to the fault, the services provided over the C-Lion1 cable are down. The cause of the fault is being investigated,” Cinia wrote in a statement.

All telecommunications running off the C-Lion1 have been cut off, according to Finnish public broadcaster YLE.

It is unclear whether the damage is the result of sabotage or weather conditions.

The Finnish Security and Intelligence Service (Supo) told YLE on Nov. 18 that it was too early to assess the cause of the cable breakage.

The agency noted that around 200 submarine cable breaks occur worldwide each year.

“The most common cause of cable breakage is human activity, such as fishing or anchoring,” a spokesperson said.

Repair work has started and Cinia said that a press conference will be held at 4 p.m. local time.

In November 2023, Estonian prosecutors said they were looking into the role of the Hong Kong-registered New Polar Bear container ship after the damage of two subsea telecoms cables in the Baltic Sea.

The two cables connecting Estonia to Finland and Sweden were damaged on Oct. 7 and Oct. 8, and an Estonia–Finland gas pipeline was broken in what Finnish investigators believe might have been sabotage. 

In May, Reuters reported that China had not responded to a six-month-old request for help with the investigation. 

The C-Lion1 cable runs alongside the Nord Stream pipelines.

The multibillion-dollar Nord Stream 1 and 2 pipelines, transporting gas under the Baltic Sea, were ruptured by a series of blasts in the Swedish and Danish economic zones in September 2022 that released vast amounts of methane into the air seven months after the Russia–Ukraine war began.

According to investigations conducted by Danish, German, and Swedish authorities, leaks in the pipelines were caused by the use of explosives.

The Polish National Public Prosecutor’s Office confirmed in August that German authorities sent a European arrest warrant (EAW) for a man wanted in connection with the Nord Stream explosions.

However, he was able to evade arrest.

The Associated Press and Reuters contributed to this report.