Guam Okinawa Kyushu Incheon (GOKI): A regional submarine cable connecting Japan and Guam
The Guam Okinawa Kyushu Incheon (GOKI) submarine cable is a fiber-optic telecommunications system spanning 4,244 kilometers, linking
Tumon Bay in Guam with
Kitakyushu and
Naha in Japan. Owned by AT&T, the cable has been listed as in service since 2013, according to GeoCables records. It serves as a key regional link between Japan and Guam, facilitating international connectivity in the Asia-Pacific region.
What makes GOKI particularly interesting is the lack of publicly disclosed technical details, such as design capacity, fiber pair count, and supplier information. This absence of transparency is unusual for a cable of its scale and importance, leaving room for speculation about its specific technological capabilities. Additionally, the recorded latency measurements highlight the gap between theoretical propagation times and real-world internet performance, shedding light on the complexities of submarine cable systems.
Quick facts
| Cable name | Guam Okinawa Kyushu Incheon (GOKI) |
| Length | 4,244 km |
| Ready for service | 2013 (GeoCables database value) |
| Owner | AT&T |
| Status | In service |
| Design capacity | Not disclosed |
| Fiber pairs | Not disclosed |
| Supplier | Not disclosed |
| Technology | Not disclosed |
| Landing points | Kitakyushu (Japan), Naha (Japan), Tumon Bay (Guam) |
Route
The GOKI cable connects three landing points: Tumon Bay in Guam, Naha in Okinawa, and Kitakyushu in Kyushu, Japan. Tumon Bay serves as a major telecommunications hub for Guam, while Naha and Kitakyushu are critical nodes in Japan's domestic and international connectivity. The cable's route traverses the Pacific Ocean, providing a direct link between Guam and Japan.
Why it was built and what it carries
The GOKI cable was likely built to enhance regional connectivity between Japan and Guam, supporting the growing demand for international bandwidth in the Asia-Pacific region. Guam serves as a strategic location for submarine cables due to its proximity to Asia and its role as a transit hub for cables linking the United States and Asia. While the specific data traffic carried by GOKI is not disclosed, it is reasonable to assume that the cable supports internet, voice, and data services for commercial and governmental users.
History: what can be established
GeoCables records indicate that the GOKI cable was ready for service in 2013. No conflicting dates have surfaced from industry sources, so this year is considered reliable. However, the absence of detailed public documentation about the cable's construction and commissioning leaves its early history somewhat opaque. AT&T's ownership suggests it was developed as part of the company's international infrastructure strategy.
Capacity and technology
The design capacity, fiber pair count, supplier, and specific technology of the GOKI cable are not disclosed in public sources. Without operator documentation, attributing these details would be speculative. Given its regional focus, the cable likely employs standard industry technologies such as dense wavelength division multiplexing (DWDM) to maximize bandwidth efficiency. However, the exact specifications remain unknown.
Latency: the physics
Theoretical one-way light propagation latency over the 4,244 km wet segment of the GOKI cable is approximately 20.8 milliseconds, with a round-trip time (RTT) floor of 41.6 milliseconds. These calculations assume light travels through fiber at speeds between 200,000 and 204,000 km/s. Real-world latency measurements, however, are higher due to additional factors such as land-based routing, terminal equipment, and network congestion.
GeoCables live measurements reveal the following RTTs over the full internet path:
- Kitakyushu -> Tumon Bay: min 49.4 ms, avg 97.6 ms
- Sydney -> Tumon Bay: min 71.0 ms, avg 247.4 ms
- Singapore -> Tumon Bay: min 66.0 ms, avg 242.3 ms
- Tumon Bay -> Kitakyushu: min 44.7 ms, avg 96.6 ms
- Sao -> Tumon Bay: min 283.9 ms, avg 287.9 ms
- Sao Paulo -> Tumon Bay: min 278.8 ms, avg 279.7 ms
These measurements highlight the disparity between theoretical and observed latency, influenced by factors beyond the cable itself.
Redundancy: what happens if it breaks
In the event of a failure, redundancy for GOKI's corridor is provided by several other cables landing at its endpoints. At Kitakyushu, the
Korea-Japan Cable Network (KJCN) offers alternative connectivity to South Korea. Naha is served by the
Japan Information Highway (JIH),
Miyazaki-Okinawa Cable (MOC), and YUI cables, while Tumon Bay hosts the
Australia-Japan Cable (AJC), linking Guam to Australia and Japan. Standard industry practices for cable repair, including deployment of specialized ships and remotely operated vehicles (ROVs), would be employed to restore service.
Bottom line
- GOKI connects Tumon Bay (Guam), Naha (Okinawa), and Kitakyushu (Kyushu, Japan).
- Owned by AT&T and listed as in service since 2013.
- Design capacity, fiber pairs, supplier, and technology are not publicly disclosed.
- Theoretical RTT floor over the wet segment is 41.6 ms; real-world latency is higher.
- Redundancy is provided by cables such as KJCN, JIH, MOC, YUI, and AJC.