Miyazaki-Okinawa Cable (MOC)

Overview

The Miyazaki-Okinawa Cable (MOC) is a submarine cable system that operates entirely within Japan's territorial waters. Commissioned in 1997, it connects Miyazaki, located on the island of Kyushu, with Naha, the capital city of Okinawa Prefecture. This cable plays a crucial role in linking the Japanese mainland to the Ryukyu Islands, providing reliable domestic connectivity between these regions. Unlike Japan's larger international submarine cable systems, the MOC is a compact, intra-national link designed to serve specific domestic communication needs.

Its strategic importance lies in bridging the gap between Kyushu and Okinawa, which are separated by the East China Sea. This connection is vital for maintaining communications infrastructure in a country composed of numerous islands, ensuring that Okinawa remains integrated with the mainland's telecommunications network. The MOC is part of Japan's extensive submarine cable network, which supports both domestic and international data traffic.

Route and Landings

The Miyazaki-Okinawa Cable has two landing points, both located within Japan. On Kyushu, the cable lands at Miyazaki, a city on the southeastern coast of the island. Miyazaki serves as a key gateway for connecting Kyushu to other parts of Japan and the broader region. On Okinawa, the cable terminates in Naha, the political and economic hub of Okinawa Prefecture. Naha is situated on Okinawa's main island, which is the largest and most populated in the Ryukyu archipelago.

The cable spans the East China Sea, a region characterized by its complex underwater topography and significant shipping traffic. This route was chosen to directly link Kyushu and Okinawa, avoiding reliance on longer and potentially less efficient paths through other domestic or international systems. The connection enhances the flow of data and communications between these two regions, which are separated by approximately 700 kilometers of ocean.

Ownership and History

The Miyazaki-Okinawa Cable is owned and operated by KDDI Corporation, one of Japan's leading telecommunications providers. KDDI manages the system independently, as it is not part of a consortium. The cable entered service in 1997, making it one of the earlier domestic submarine cable systems in Japan's modern telecommunications era.

Its deployment coincided with a period of rapid expansion in Japan's submarine cable infrastructure during the late 1990s. While many of Japan's submarine cables are designed for international connectivity, the MOC was specifically developed to address domestic needs. Over its operational lifespan, the cable has provided stable and efficient connectivity between Kyushu and Okinawa, supporting regional development and communication in these areas.

What Our Measurements Show

Our monitoring of the Miyazaki-Okinawa Cable reveals consistent performance across its 159 measured corridors. The best round-trip time (RTT) recorded is 256 milliseconds, while the average RTT is slightly higher at 269 milliseconds. These figures indicate reliable latency levels for a domestic submarine cable of its size and scope.

The data suggests that the MOC is optimized for its intended purpose of intra-national connectivity. Its performance is particularly important for Okinawa, which relies on this direct link to maintain seamless communication with the mainland. The cable's stable latency supports a range of applications, from internet services to enterprise communications, ensuring that the Ryukyu Islands remain integrated with Japan's broader telecommunications network.