JAKO

What Jako is

Jako is a planned short-haul submarine cable that will link South Korea and Japan across the Korea Strait. It is a compact system, about 260 km, with service expected around 2027. Its owners are a mix of cloud and regional players: Amazon Web Services, Microsoft, Arteria and Dreamline.

Route and landing points

The cable connects Busan in South Korea to Fukuoka in Japan, two cities that sit close across one of the busiest short sea crossings in Asia.

Why the route matters

Korea and Japan are two of the largest internet markets in Asia, and the short hop between them carries enormous traffic. Existing cables on this crossing are heavily used, so a fresh, high-capacity link adds both headroom and a backup path. For the cloud providers on the consortium, low-latency capacity between Korean and Japanese data centres is directly useful for cloud and content services, and Busan is also a junction where several longer-haul Pacific cables come ashore.

A short link with outsized value

Jako is short, but short cables on dense, high-value crossings matter as much as long-haul systems. The Korea Strait is a natural choke point: a small number of cables carry a large share of Korea-Japan traffic, so each added route meaningfully changes how much can fail over if one is cut.

Regional context

The waters between Busan and Fukuoka are crowded with ferries, fishing boats and merchant shipping, all working in a shallow strait. That traffic, passing over a tight cluster of cables, is the main everyday risk to systems like Jako, where an anchor or a trawl can reach the seabed. Both Korea and Japan invest in cable-protection zones and active monitoring along this strait, but the sheer density of vessel traffic keeps the everyday risk of accidental damage high, which is part of why operators keep adding parallel routes.

How GeoCables will track it

Once Jako is live, GeoCables can monitor the paths that rely on the Korea-Japan crossing and watch vessels over its short corridor. On a choke point this concentrated, an early signal that one cable is degrading is valuable precisely because so much traffic shares so few routes.

What is known and what is not

The owners (Amazon Web Services, Microsoft, Arteria and Dreamline), the endpoints and the planned service window around 2027 are on record. The capacity, the supplier and the exact in-service date are not yet confirmed. Where a detail is not public, we mark it as unknown rather than guess.