Scandinavian Ring South: A Short-Distance Submarine Link Between Sweden and Denmark
The Scandinavian Ring South is a submarine cable connecting
Bunkeflostand in Sweden to
Dragor in Denmark, spanning a modest distance of 21 kilometers. Owned by Arelion, the cable has been listed as in service since its recorded ready-for-service (RFS) year of 2000. While its short length makes it unique among submarine cables, much about its technical specifics, such as design capacity and fiber pair configuration, remains undisclosed in public sources.
What is particularly interesting about the Scandinavian Ring South is its geographical placement and purpose. Unlike long-haul transoceanic cables, this link serves as a cross-border connection within the Scandinavian region, bridging two closely situated countries. While its latency potential is extremely low due to the short distance, real-world measurements are unavailable, leaving some uncertainty about its operational characteristics.
Quick facts
| Cable name | Scandinavian Ring South |
| Length | 21 km |
| Ready-for-service year | 2000 (GeoCables database value; industry sources may differ) |
| Owners | Arelion |
| Status | In service |
| Design capacity | Not disclosed |
| Fiber pairs | Not disclosed |
| Supplier | Not disclosed |
| Technology | Not disclosed |
| Landing points | Bunkeflostand (Sweden); Dragor (Denmark) |
| Computed latency (one-way) | ≈ 0.1 ms |
| Computed latency (RTT floor) | ≈ 0.2 ms |
| Live latency measurements | None available |
Route
The Scandinavian Ring South connects Bunkeflostand, located near Malmö in southern Sweden, to Dragor, a town on the eastern coast of Denmark near Copenhagen. The cable crosses the Øresund Strait, a narrow body of water separating the two countries. This corridor is geographically significant as it supports regional connectivity in an area with dense population centers and significant economic activity.
Why it was built and what it carries
The Scandinavian Ring South was likely built to provide a reliable and low-latency link between Sweden and Denmark, complementing terrestrial infrastructure such as the Øresund Bridge. Submarine cables in such short corridors often serve as critical redundancy for land-based systems and facilitate high-speed data transmission across borders. However, the specific traffic carried by this cable-whether predominantly consumer internet, enterprise data, or other forms of communication-has not been disclosed by Arelion.
History: what can be established
The GeoCables database records the Scandinavian Ring South as ready for service in 2000. However, industry sources occasionally list different RFS years for submarine cables, which could be due to discrepancies in documentation, upgrades, or delays in commissioning. Without corroborating details, attributing any alternative RFS year would be speculative.
Capacity and technology
Publicly available data does not disclose the design capacity, fiber pair count, or the technology employed in the Scandinavian Ring South. Without operator documentation, it is impossible to determine whether the cable has undergone upgrades since its deployment or what its maximum throughput might be. This lack of transparency is not uncommon for smaller regional cables, which often receive less attention than larger transoceanic systems.
Latency: the physics
The theoretical one-way latency for light propagation over the cable's 21-kilometer wet segment is approximately 0.1 milliseconds, assuming optimal conditions and light traveling at speeds between 200,000 and 204,000 kilometers per second in fiber. The round-trip time (RTT) floor for this segment is therefore calculated at approximately 0.2 milliseconds. However, real-world latency will be higher due to additional factors such as land-based segments, terminal equipment, and routing inefficiencies. No live measurements are currently available to verify the cable's operational latency.
Redundancy: what happens if it breaks
In the event of a failure, redundancy for the Scandinavian Ring South would likely rely on terrestrial routes such as the Øresund Bridge, which carries both road and rail traffic as well as fiber-optic cables. Other regional submarine cables may also provide alternative paths, though their specific configurations and capacities are not detailed in the GeoCables database. Repairs to submarine cables typically involve locating the fault, deploying specialized cable ships, and restoring connectivity-a process that can take days to weeks depending on the nature of the damage and weather conditions.
Bottom line
- The Scandinavian Ring South is a 21-kilometer submarine cable linking Sweden and Denmark across the Øresund Strait.
- Its ready-for-service year is recorded as 2000, though alternative dates may exist in industry sources.
- Owned by Arelion, the cable remains in service, but its design capacity, fiber pairs, supplier, and technology are not publicly disclosed.
- Theoretical latency is extremely low due to the short distance, but no live measurements are available.
- Redundancy is likely provided by terrestrial routes such as the Øresund Bridge and potentially other regional cables.