Thetis Express: A Submarine Cable Connecting Greek Islands
The Thetis Express is a submarine telecommunications cable owned by Vodafone, connecting
Athens,
Heraklion, and
Milos in Greece. Spanning approximately 340 km, the cable is listed as in service, with its ready-for-service (RFS) year recorded in GeoCables as 2027. This cable serves as a regional link between mainland Greece and its islands, facilitating improved connectivity in the eastern Mediterranean.
What stands out about the Thetis Express is the uncertainty surrounding its technical specifications and operational details. Publicly available data does not disclose key parameters such as design capacity, fiber pair count, supplier, or technology used. Additionally, while GeoCables lists its RFS year as 2027, it is worth investigating whether industry sources corroborate this timeline or suggest an earlier operational date.
Quick facts
| Cable name |
Thetis Express |
| Length |
340 km |
| Ready-for-service year |
2027 (GeoCables database; industry sources not consulted) |
| Owner |
Vodafone |
| Status |
In service |
| Design capacity |
Not disclosed |
| Fiber pairs |
Not disclosed |
| Supplier |
Not disclosed |
| Technology |
Not disclosed |
| Landing points |
Athens (Greece), Heraklion (Greece), Milos (Greece) |
Route
The Thetis Express connects three landing points within Greece: Athens on the mainland, Heraklion on the island of Crete, and Milos in the Cyclades. This route is geographically significant as it links key population centers and economic hubs in the eastern Mediterranean. Athens serves as a major gateway for international and regional connectivity, while Heraklion and Milos are important for local communications and tourism-driven economies.
Why it was built and what it carries
Thetis Express was likely built to enhance connectivity between the Greek mainland and its islands, addressing the need for reliable and high-speed telecommunications in the region. Submarine cables like Thetis Express typically carry internet traffic, voice communications, and data for businesses and consumers. Given Vodafone's ownership, it is plausible that the cable plays a role in supporting the company's mobile and broadband services in Greece.
History: what can be established
GeoCables records the ready-for-service year of Thetis Express as 2027. However, since the cable is listed as "in service," this raises questions about whether it became operational earlier than expected. Industry sources have not been consulted to confirm or dispute the 2027 date, leaving room for potential discrepancies. Possible explanations for the conflict include errors in database entry, delays in project completion, or premature listing of the cable's operational status.
Capacity and technology
Publicly available information does not disclose the design capacity, fiber pair count, supplier, or technology used in Thetis Express. Without operator documentation, it is impossible to state these parameters definitively. The lack of transparency is not uncommon in the submarine cable industry, particularly for regional cables serving smaller markets.
Latency: the physics
The theoretical one-way light propagation latency for Thetis Express over its 340 km wet segment is approximately 1.7 ms, resulting in a round-trip time (RTT) floor of 3.3 ms. Real-world latency measurements, however, will exceed this theoretical floor due to additional factors such as land-based network tails, terminal equipment processing, and routing delays.
GeoCables' live latency measurements, conducted via remote probes, show values far exceeding the physical floor, with paths like Minsk to Sydney exhibiting a minimum RTT of 304.4 ms. These measurements reflect the full internet path rather than the cable itself, and any values below the physical floor (e.g., the 0.2 ms minimum reported for Sydney to Sydney) are measurement artifacts caused by rate-limited ICMP replies. Such artifacts should not be interpreted as the cable's actual performance.
Redundancy: what happens if it breaks
In the event of a fault in Thetis Express, redundancy in the Athens landing point is provided by other cables, including
EMC West-1,
MedNautilus Submarine System, and
Medusa Submarine Cable System. These alternatives may mitigate disruptions to international and regional connectivity. Repairing faults in submarine cables typically involves deploying specialized cable ships to locate, retrieve, and mend the damaged section-a process that can take days or weeks depending on the severity of the issue and environmental conditions.
Bottom line
- Thetis Express is a submarine cable connecting Athens, Heraklion, and Milos in Greece.
- Its recorded ready-for-service year is 2027, though its operational status raises questions about potential discrepancies.
- Key technical specifications, including design capacity and fiber pair count, are not publicly disclosed.
- The theoretical RTT floor for its wet segment is 3.3 ms, but real-world latency is higher due to additional network factors.
- Redundancy at Athens is provided by other cables, mitigating potential disruptions.