Jeju-Udo

Overview

Jeju-Udo is a domestic submarine cable system located entirely within South Korea. At just 3 km in length, it connects two points within South Korean waters, serving a short intra-national corridor rather than an international or intercontinental route. The cable links the coastal landing point of Goseong-ri with the island of Udo, providing a dedicated submarine connection to the latter.

Route and Landings

Both landing points are situated in South Korea. The cable comes ashore at Goseong-ri and at Udo, spanning approximately 3 km of seabed between the two sites. Udo is a small island located off the northeastern coast of Jeju Island, and Goseong-ri sits on the nearest adjacent coastline.

Ownership and Operators

Jeju-Udo is jointly owned by four South Korean telecommunications companies: KCTV Jeju Broadcasting, KT, LG Uplus, and SK Telecom (SKT). KT, LG Uplus, and SK Telecom are among South Korea's largest national telecoms carriers, while KCTV Jeju Broadcasting is a regional broadcaster and cable operator based on Jeju Island.

Status and Timeline

The cable entered service in 2023 and has been operational for approximately three years. No end-of-service date is recorded.

Regional Context

South Korea's submarine cable infrastructure spans 14 cables across 10 landing points, with an average cable length of around 9,233 km, reflecting the country's extensive international connectivity. Jeju-Udo occupies a distinctly different position within this landscape: at 3 km, it is the shortest cable among those touching South Korea, sitting below the full range of international systems serving the country. Cables such as APCN-2, EAC-C2C, the Trans-Pacific Express (TPE) Cable System, New Cross Pacific (NCP), and the forthcoming E2A and Southeast Asia-Japan Cable 2 (SJC2) all represent long-haul international routes measured in thousands of kilometres. Jeju-Udo's purpose is local rather than intercontinental, filling a specific geographic need that larger systems are not designed to address.

Strategic Role

Jeju-Udo provides direct submarine connectivity between the South Korean mainland coast at Goseong-ri and the island of Udo, supporting the island's access to the national telecommunications network. The involvement of four operators — including three national carriers and a regional broadcaster — reflects a shared interest in extending reliable connectivity to an island community that is otherwise isolated by water, even across a very short distance.