C-Lion1

Overview

C-Lion1 is a submarine cable system spanning 1,172 kilometres across the Baltic Sea, connecting Finland and Germany. It forms a direct link between the Finnish and German coasts, serving one of the shorter but less densely cabled corridors in Northern Europe. Owned entirely by Finnish telecommunications infrastructure company Cinia Oy, C-Lion1 stands as a notable bilateral cable in the Finland–Germany corridor.

Route and Landings

In Finland, C-Lion1 lands at two locations: Hanko, on the southern tip of the Finnish mainland, and Helsinki, the Finnish capital. These two Finnish landing points provide geographic diversity within the country.

In Germany, the cable comes ashore at Rostock, a port city on the southern Baltic coast. The combination of these three landing points establishes a direct undersea path across the Baltic between the two countries.

Ownership and Operators

C-Lion1 is owned solely by Cinia Oy, a Finnish state-majority-owned company specialising in network infrastructure and data connectivity services. As the sole owner, Cinia Oy operates the cable independently rather than through a consortium arrangement.

Status and Timeline

C-Lion1 entered service in 2016 and has now been operational for approximately ten years. It continues to operate as a live cable system connecting its Finnish and German landing points.

Regional Context

Within the Finland–Germany corridor, C-Lion1 at 1,172 kilometres is longer than 92% of the other cables touching either of these two countries, reflecting the relatively direct trans-Baltic routing between Hanko and Helsinki in Finland and Rostock in Germany. Regional peers in this corridor include STO-HEL-One, BCS North Phase 1 and Phase 2, the forthcoming Aurora, and Mjolner East — most of which are considerably shorter systems. Atlantic Crossing-1 is a far longer transatlantic system also landing in Germany, serving a different purpose entirely.

Measured performance over the past 60 days shows an average round-trip latency of 69.5 milliseconds through C-Lion1, with a best recorded measurement of 33.3 milliseconds across 100 ping tests.

Strategic Role

By directly connecting two Finnish landing points with the German Baltic coast, C-Lion1 provides a dedicated subsea link between Finland and one of Central Europe's major connectivity hubs. The cable's length, relative to other systems in the same corridor, reflects the directness of the Baltic Sea crossing it accomplishes. With landings split between Hanko and Helsinki on the Finnish side, the system also offers some degree of geographic redundancy for traffic entering or leaving Finland via this route.