Kuroshima, Japan

Kuroshima: A Small Link in Japan's Vast Submarine Cable Network

Kuroshima, a remote landing point in Japan's Mishima Village, hosts a single submarine cable: the Mishima Village cable. This cable, which became ready for service in 2010, connects Kuroshima to three other landing points within Japan: Iojima, Makurazaki, and Takeshima. At just 192 km in length, the cable is relatively short compared to Japan's national average cable length of 5696 km, yet it plays a meaningful role in stitching together the country's coastal communities.

Connectivity in Isolation

Kuroshima stands in stark contrast to Japan's major cable hubs, such as Shima (12 cables) and Maruyama (9 cables). While these hubs are bustling with international and domestic connectivity, Kuroshima operates on a much smaller scale. Its single cable is entirely domestic, linking it to nearby islands and the mainland rather than reaching out to other countries. Despite its modest infrastructure, Kuroshima's position in the Mishima Village cable chain ensures that it remains connected to the broader Japanese network. This localized approach to connectivity reflects the unique geography of Japan, where small islands like Kuroshima rely on targeted infrastructure to maintain their links to the outside world. Unlike larger hubs that serve as gateways to international networks, Kuroshima's cable is a lifeline for local communication and data transfer.

Latency: A Window into Performance

GeoCables' latency measurements provide a glimpse into the performance of the Mishima Village cable. Over 36 completed checks from nine source cities, the average round-trip latency to Kuroshima was 280 ms, with the best observed latency at 80 ms. While these numbers are higher than what might be expected for major hubs, they are consistent with the cable's role in connecting remote areas. The latency reflects the physical distance and the nature of the infrastructure, underscoring the challenges of serving smaller, isolated communities.

Positioning Kuroshima in Japan's Cable Landscape

Japan is home to 51 submarine cables spread across 68 landing points, making it one of the most connected countries in the world. Kuroshima ranks in the top 68% of landing points by cable count, highlighting its modest but functional role in the network. While it lacks the density of cables found in hubs like Chikura (8 cables) or Naha (4 cables), Kuroshima's single cable ensures that Mishima Village remains connected to the rest of Japan. For Kuroshima, the Mishima Village cable is not about global connectivity but about maintaining links within Japan's intricate web of islands. It serves as a reminder that even the smallest landing points contribute to the nation's overall network, ensuring that no community is left behind.