C-Lion1: A Submarine Cable Connecting Finland and Germany
C-Lion1 is a submarine telecommunications cable system linking Finland and Germany across the Baltic Sea. Owned by Cinia Oy, a Finnish ICT company, the cable spans approximately 1172 kilometers and has been operational since 2016, according to GeoCables database records. It provides a direct route between
Hanko and
Helsinki in Finland and
Rostock in Germany, serving as a key corridor for data transmission between Northern and Central Europe.
What makes C-Lion1 particularly interesting is the lack of publicly disclosed information regarding its design capacity, fiber pair count, supplier, and technology. This absence of details highlights the proprietary nature of some submarine cable systems, leaving analysts reliant on indirect measurements and industry speculation to assess its capabilities. Additionally, the cable's latency characteristics and its role in a heavily interconnected region raise questions about its impact on regional and international connectivity.
Quick facts
| Length | 1172 km |
| Ready-for-Service Year | 2016 (GeoCables database; no conflicting sources identified) |
| Owner | Cinia Oy |
| Status | In service |
| Design Capacity | Not disclosed |
| Fiber Pairs | Not disclosed |
| Supplier | Not disclosed |
| Technology | Not disclosed |
| Landing Points | Hanko (Finland), Helsinki (Finland), Rostock (Germany) |
🗺 Show C-Lion1 on the interactive cable map
Route
C-Lion1 connects three landing points: Hanko and Helsinki in Finland and Rostock in Germany. Hanko, located on Finland's southern coast, is a strategic location for submarine cables due to its proximity to the Baltic Sea. Helsinki, Finland's capital, serves as a major hub for telecommunications and data centers. Rostock, situated on Germany's Baltic coast, provides access to Central European networks and serves as a gateway for data traffic between Northern Europe and the rest of the continent.
The Baltic Sea corridor is a highly interconnected region, with numerous other submarine cables landing at these points. At Hanko, cables such as
BCS North - Phase 1 and
Eastern Light Sweden-Finland I and II provide additional redundancy. Helsinki hosts a wide array of cables, including
Baltic Sea Submarine Cable, Finland-Estonia connections, and
Mjolner East. Rostock is also a landing site for
Elektra-GlobalConnect 1 (GC1) and
GlobalConnect-KPN, further enhancing the area's connectivity.
Why it was built and what it carries
C-Lion1 was built to address the growing demand for high-speed, low-latency connectivity between Finland and Germany, as well as to support Finland's ambitions to become a digital hub for Northern Europe. By providing a direct route across the Baltic Sea, the cable enhances data transmission efficiency and reduces reliance on terrestrial networks that may be subject to congestion or geopolitical risks.
While specific details about the cable's traffic composition are not publicly disclosed, it is likely that C-Lion1 carries a mix of commercial, governmental, and academic data. Given Finland's strong focus on technology and innovation, the cable may also support data-intensive applications such as cloud computing, artificial intelligence, and scientific research.
History: what can be established
C-Lion1 was recorded as ready for service in 2016, according to GeoCables data. No conflicting sources have been identified regarding this date, suggesting that this timeline is widely accepted. Cinia Oy, the cable's owner, has positioned itself as a key player in the region's telecommunications infrastructure, leveraging C-Lion1 to enhance Finland's connectivity with Central Europe.
Capacity and technology
Publicly available information does not disclose the design capacity, fiber pair count, supplier, or technology of C-Lion1. Without operator documentation, attributing specific technical characteristics to the cable would be speculative. However, given its relatively recent deployment in 2016, it is reasonable to assume that the cable employs modern optical fiber technology capable of supporting high data rates.
Latency: the physics
The computed one-way light propagation latency for C-Lion1 over its 1172 km wet segment is approximately 5.7 milliseconds, with a theoretical round-trip time (RTT) floor of 11.5 milliseconds. Real-world latency measurements, however, are higher due to additional factors such as land tails, terminal equipment, and routing.
GeoCables' live measurements provide insights into end-to-end latency over the full internet path, not the cable itself. For example:
- Rostock -> Helsinki: min 24.0 ms, avg 73.4 ms
- Helsinki -> Rostock: min 19.6 ms, avg 30.2 ms
- Sydney -> Helsinki: min 273.2 ms, avg 273.3 ms
- Saint Petersburg -> Helsinki: min 9.8 ms, avg 10.4 ms (artifact below physical floor - not real path latency)
- Minsk -> Helsinki: min 51.8 ms, avg 55.3 ms
- Minsk -> Rostock: min 38.5 ms, avg 39.0 ms
The Saint Petersburg -> Helsinki minimum latency of 9.8 ms is flagged as an artifact, likely caused by rate-limited ICMP replies from intermediate routers. Analysts should treat this value with caution.
Redundancy: what happens if it breaks
In the event of a failure, the Baltic Sea region offers numerous alternative submarine cables to reroute traffic. At Hanko, redundancy is provided by BCS North - Phase 1 and Eastern Light Sweden-Finland cables. Helsinki is a landing point for several cables, including the Baltic Sea Submarine Cable and Finland-Estonia connections. Rostock's alternatives include Elektra-GlobalConnect 1 (GC1) and GlobalConnect-KPN. Standard industry practices for submarine cable repair, such as deploying cable ships and remotely operated vehicles (ROVs), would be employed to restore service.
Bottom line
- C-Lion1 spans 1172 km, connecting Finland and Germany via the Baltic Sea.
- Owned by Cinia Oy and operational since 2016.
- Design capacity, fiber pairs, supplier, and technology are not publicly disclosed.
- Computed latency floor: one-way ≈ 5.7 ms, RTT ≈ 11.5 ms; real-world latency is higher.
- Redundancy provided by numerous cables in the Baltic Sea region.