Baltic Sea Submarine Cable: connecting Finland, Sweden, and Estonia
The Baltic Sea Submarine Cable is a submarine telecommunications cable spanning 1,042 km across the Baltic Sea, linking
Helsinki (Finland),
Stockholm (Sweden), and
Tallinn (Estonia). Owned by CITIC Telecom International, the cable has been listed as in service since 2000 according to GeoCables data. Its exact design capacity, fiber pair count, supplier, and technology details are not publicly disclosed, making certain aspects of its technical specifications unclear.
What stands out about this cable is its role in connecting three major cities in the Baltic region, each of which serves as a hub for other submarine cables. The cable's presence in this corridor highlights the dense network of connectivity in Northern Europe. However, the absence of detailed public information about its technology and capacity makes it challenging to assess its specific contribution to regional bandwidth and redundancy.
Quick facts
| Name | Baltic Sea Submarine Cable |
| Length | 1,042 km |
| Ready for Service (RFS) | 2000 (GeoCables database value; conflicting dates not surfaced) |
| Owners | CITIC Telecom International |
| Status | In service |
| Design Capacity | Not disclosed |
| Fiber Pairs | Not disclosed |
| Supplier | Not disclosed |
| Technology | Not disclosed |
| Landing Points | Helsinki (Finland), Stockholm (Sweden), Tallinn (Estonia) |
Route
The Baltic Sea Submarine Cable connects three key cities in the Baltic region: Helsinki, Stockholm, and Tallinn. These cities are major hubs for telecommunications and serve as landing points for numerous other cables. Helsinki is a landing site for nine other submarine cables, including
C-Lion1 and
Eastern Light Sweden-Finland I. Stockholm hosts connections to
Sweden-Latvia and Eastern Light Sweden-Finland I. Tallinn is linked to Finland via multiple cables, such as
Finland-Estonia 2 (EESF-2) and
Finland Estonia Connection 1 (FEC-1), as well as Sweden through
Sweden-Estonia (EE-S 1).
Why it was built and what it carries
The Baltic Sea Submarine Cable was likely built to enhance connectivity among Finland, Sweden, and Estonia, countries with strong economic and technological ties. It provides international bandwidth for telecommunications, internet traffic, and potentially private data networks. While its design capacity is not disclosed, it is reasonable to assume that the cable contributes to the high-speed data exchange required in this region, which is known for its advanced digital infrastructure.
History: what can be established
GeoCables data lists the cable's ready-for-service (RFS) year as 2000. No conflicting dates have been surfaced from industry sources, so this year is taken as accurate. CITIC Telecom International is recorded as the cable's owner, but further historical details about its construction, supplier, or operational milestones are not publicly available.
Capacity and technology
Public sources do not disclose the cable's design capacity, fiber pair count, or specific technology employed. Without documentation from the operator, these details remain speculative. Submarine cables in this region typically use dense wavelength division multiplexing (DWDM) technology to maximize bandwidth, but attributing this to the Baltic Sea Submarine Cable without confirmation would be unwarranted.
Latency: the physics
The computed one-way light propagation latency over the cable's 1,042 km wet segment is approximately 5.1 ms, resulting in a theoretical round-trip time (RTT) floor of 10.2 ms. Real-world latency measurements, however, are higher due to additional factors such as land tails, terminal equipment, and routing.
Live measurements conducted via remote probes show significant variability. For example:
- Helsinki -> Stockholm: Minimum 10.0 ms, average 54.6 ms over 138 checks. The minimum is flagged as an artifact, as it falls below the physical floor.
- Stockholm -> Helsinki: Minimum 1.6 ms, average 4.8 ms over 40 checks. Again, the minimum is flagged as an artifact.
- Minsk -> Stockholm: Minimum 20.0 ms, average 20.3 ms over 4 checks.
- Sydney -> Stockholm: Minimum and average 263.6 ms over 3 checks.
- Saint Petersburg -> Stockholm: Minimum 16.3 ms, average 16.5 ms over 3 checks.
- Tbilisi -> Stockholm: Minimum and average 78.2 ms over 1 check.
The flagged artifacts highlight the importance of interpreting measurements cautiously, as they often reflect the full internet path rather than the cable's direct performance.
Redundancy: what happens if it breaks
The Baltic Sea Submarine Cable operates in a corridor with extensive redundancy. Helsinki, Stockholm, and Tallinn are connected to multiple other cables, ensuring alternative routes for data traffic in case of failure. For example, Helsinki is linked to C-Lion1 and
Finland-Estonia 3 (EESF-3), while Tallinn has connections to Sweden-Estonia (EE-S 1) and
Finland Estonia Connection 2 (FEC-2). Repair logistics would follow standard industry practices, including cable surveys, fault localization, and deployment of cable ships for repairs.
Bottom line
- The Baltic Sea Submarine Cable spans 1,042 km, connecting Helsinki, Stockholm, and Tallinn.
- Owned by CITIC Telecom International, it has been in service since 2000.
- Key technical details such as design capacity and fiber pairs are not publicly disclosed.
- Computed latency over the wet segment is approximately 10.2 ms RTT, with real-world measurements showing variability.
- The cable operates in a highly redundant corridor, minimizing the impact of potential failures.