POSEIDON: A regional submarine cable connecting Cyprus
The POSEIDON submarine cable is an 800-kilometer system connecting two landing points in Cyprus:
Pentaskhinos and
Yeroskipos. Owned by Ocean Specialists, Inc (OSI), it has been listed as in service since 2014 according to GeoCables records. While the cable's design capacity, fiber pair count, supplier, and specific technological details are not publicly disclosed, its role in regional connectivity is notable due to the concentration of other submarine cables at its landing points.
What makes POSEIDON particularly interesting is the lack of detailed public information about its specifications and performance. This absence raises questions about its operational role in the broader network of submarine systems in the Eastern Mediterranean. Furthermore, the cable's relatively short length suggests it primarily serves intra-island connectivity or acts as a secondary link for redundancy purposes.
Quick facts
| Name | POSEIDON |
| Length | 800 km |
| Ready for Service (RFS) | 2014 (GeoCables database value) |
| Owner | Ocean Specialists, Inc (OSI) |
| Status | In service |
| Design capacity | Not disclosed |
| Fiber pairs | Not disclosed |
| Supplier | Not disclosed |
| Technology | Not disclosed |
| Landing points | Pentaskhinos (Cyprus); Yeroskipos (Cyprus) |
Route
POSEIDON connects two locations on the island of Cyprus: Pentaskhinos on the southern coast and Yeroskipos on the western coast. Both landing points are hubs for multiple submarine cables, reflecting Cyprus's strategic importance in the Eastern Mediterranean telecom corridor. Pentaskhinos hosts cables such as
CADMOS,
CADMOS-2,
MedNautilus Submarine System,
TE North/TGN-Eurasia/SEACOM/Alexandros/Medex, and
UGARIT. Similarly, Yeroskipos is a landing site for cables including
Blue,
Exelera North,
Hawk,
Medusa Submarine Cable System, and the
PEACE Cable.
Why it was built and what it carries
The precise motivations behind the construction of POSEIDON are not documented in publicly available sources. However, it is plausible that the cable was designed to enhance intra-island connectivity within Cyprus or to provide additional redundancy for the many international cables landing at Pentaskhinos and Yeroskipos. Given the density of cables at these sites, POSEIDON may also serve as a short-haul link facilitating traffic aggregation or redistribution.
History: what can be established
POSEIDON is recorded as having been ready for service in 2014 in the GeoCables database. If other industry sources suggest a different RFS year, this has not been surfaced in publicly available data. The absence of documented conflicts about its operational timeline makes it difficult to explore discrepancies or alternative narratives.
Capacity and technology
The design capacity, fiber pair count, supplier, and specific technological features of POSEIDON are not disclosed in public sources. Without operator documentation, attributing any specific figures or technologies would be speculative. This lack of transparency is not uncommon for smaller regional cables, especially those serving niche or intra-island purposes.
Latency: the physics
The theoretical one-way light propagation time over POSEIDON's 800-kilometer length is approximately 3.9 milliseconds, assuming a speed of 200,000 to 204,000 kilometers per second in fiber. The theoretical round-trip time (RTT) over the wet segment is roughly 7.8 milliseconds. However, real-world RTT measurements would be higher due to additional factors such as land tails, terminal equipment delays, and routing inefficiencies. No live latency measurements are currently available for POSEIDON.
Redundancy: what happens if it breaks
In the event of a failure on POSEIDON, the presence of numerous other cables at its landing points provides substantial redundancy. For Pentaskhinos, alternatives include CADMOS, CADMOS-2, MedNautilus Submarine System, TE North/TGN-Eurasia/SEACOM/Alexandros/Medex, and UGARIT. At Yeroskipos, redundancy is supported by cables such as Blue, Exelera North, Hawk, Medusa Submarine Cable System, and the PEACE Cable. Standard industry practices for submarine cable repair, including vessel mobilization, cable recovery, and splicing, would apply to POSEIDON in the event of a fault.
Bottom line
- POSEIDON is an 800-kilometer submarine cable connecting Pentaskhinos and Yeroskipos in Cyprus.
- Owned by Ocean Specialists, Inc (OSI), it has been listed as in service since 2014.
- Key specifications such as design capacity, fiber pairs, supplier, and technology are not publicly disclosed.
- Its landing points host a dense concentration of other submarine cables, providing redundancy.
- Theoretical latency over the wet segment is approximately 7.8 milliseconds RTT, but real-world values would be higher.
- POSEIDON's role in regional connectivity remains unclear due to limited public information.