Minamidaito Island: Submarine Cable Connecting Okinawa Prefecture
The Minamidaito Island submarine cable is a 410-kilometer system that links
Itoman on Okinawa Island with Minamidaito Island, both located in Japan. Owned by Okinawa Prefecture, this cable is listed as in service and has been operational since 2011 according to GeoCables database records. It serves as a critical link for telecommunications in the region, connecting remote islands to the broader network infrastructure of Okinawa.
What stands out about this cable is the scarcity of publicly disclosed technical details. Key specifications such as design capacity, fiber pair count, supplier, and technology are not documented in available sources, leaving room for speculation but no definitive answers. Additionally, its role in redundancy and its relationship to other cables serving the region, such as the
Okinawa Remote Islands cable at Itoman and the
Daito Loop cable at Minamidaito, provide context for understanding its significance.
Quick facts
| Length |
410 km |
| Ready for Service (RFS) |
2011 (GeoCables database; no conflicting data surfaced) |
| Owner |
Okinawa Prefecture |
| Status |
In service |
| Design Capacity |
Not disclosed |
| Fiber Pairs |
Not disclosed |
| Supplier |
Not disclosed |
| Technology |
Not disclosed |
| Landing Points |
Itoman (Japan); Minamidaito (Japan) |
| Other Cables at Itoman |
Okinawa Remote Islands |
| Other Cables at Minamidaito |
Daito Loop |
🗺 Show Minamidaito Island on the interactive cable map
Route
The cable connects Itoman, a city on the southern tip of Okinawa Island, to Minamidaito Island, a remote island located approximately 410 kilometers to the east. This eastward route traverses a section of the Philippine Sea, a region known for its deep waters and tectonic activity. The cable's landing points are strategically chosen to integrate Minamidaito Island into Okinawa Prefecture's telecommunications network.
Why it was built and what it carries
The Minamidaito Island cable was built to provide reliable connectivity to Minamidaito Island, a remote community that would otherwise face significant challenges in accessing modern telecommunications services. By linking the island to Itoman, the cable enables internet access, voice communication, and data transfer for residents, businesses, and local government operations. It also supports broader regional connectivity goals, ensuring that Okinawa Prefecture’s remote islands are integrated into Japan’s national network.
History: what can be established
According to GeoCables records, the cable was ready for service in 2011. No conflicting data from industry sources has surfaced, so this date is considered reliable. The lack of publicly disclosed information about its supplier, design, and construction timeline makes it difficult to provide a detailed history of its development. However, its operation since 2011 suggests that it has been successfully maintained and has fulfilled its intended purpose.
Capacity and technology
Public sources do not disclose the design capacity, fiber pair count, or specific technology used in the Minamidaito Island cable. Without operator documentation, attributing these specifications would be speculative. It is likely that the cable uses standard submarine cable technologies for its time, such as dense wavelength division multiplexing (DWDM), but this cannot be confirmed without further information.
Latency: the physics
The computed one-way light propagation latency over the cable’s 410-kilometer length is approximately 2.0 milliseconds, with a theoretical round-trip time (RTT) floor of 4.0 milliseconds. These figures represent the propagation delay in the fiber itself, assuming light travels at 200,000 to 204,000 kilometers per second. Real-world latency measurements would be higher due to additional factors such as signal processing in terminal equipment, routing through land-based networks, and the presence of land tails at both ends. No live measurements for this cable are available, so actual performance remains undocumented.
Redundancy: what happens if it breaks
In the event of a failure, redundancy for Minamidaito Island’s connectivity would likely depend on the Daito Loop cable, which also lands at Minamidaito. At Itoman, the Okinawa Remote Islands cable could provide alternative routing for traffic. However, the extent to which these systems are interconnected and capable of fully compensating for outages on the Minamidaito Island cable is not publicly disclosed. Repairing submarine cables typically involves deploying specialized cable ships to locate, retrieve, and repair the damaged segment, a process that can take days or weeks depending on weather and logistical challenges.
Bottom line
- The Minamidaito Island cable is a 410-kilometer submarine system connecting Itoman and Minamidaito Island in Okinawa Prefecture, Japan.
- Operational since 2011, it is owned by Okinawa Prefecture and listed as in service.
- Key technical details such as design capacity, fiber pairs, supplier, and technology are not publicly disclosed.
- Its theoretical latency floor is approximately 4.0 milliseconds round-trip over the wet segment, but real-world latency would be higher.
- Redundancy may be supported by the Daito Loop and Okinawa Remote Islands cables, but details are unclear.