Southeast Asia’s (SEA) subsea cable network is seeing a fresh wave of investment, with new systems entering service, existing routes being upgraded and new international links moving ahead. The developments span Singapore, Indonesia, Thailand, Malaysia and Vietnam, with projects aimed at adding capacity as well as opening alternative routes between the region and major markets in India, China, Australia and the US.
A look at some of the subsea cable systems, recent developments in the region, challenges being faced and what the future holds…
Major regional cable systems
SEA-H2X
China Mobile International’s Southeast Asia-Hainan-Hong Kong (SEA-H2X) submarine cable system entered commercial service in July 2026, following system acceptance testing. The approximately 5,746 km system comprises eight fibre pairs and connects Hong Kong and Hainan with landing points across SEA. It has a designed capacity of 200 Tbps and is intended to provide a high-capacity, low-latency route between China and SEA.
ALC
The approximately 6,200 km Asia Link Cable (ALC), led by China Telecom and developed with 13 Asia-Pacific operators, connects Hong Kong and Hainan with Singapore, the Philippines, Vietnam, Brunei and Malaysia. The system has 13 fibre pairs and more than 325 Tbps of designed capacity.
SJC2
Southeast Asia-Japan Cable 2 (SJC2) is a 10,500 km submarine cable connecting locations across Asia, including Singapore, Thailand, Cambodia, Vietnam, Hong Kong, Taiwan, mainland China, South Korea and Japan. The system can transmit more than 126 Tbps and entered operation in July 2025. It provides additional connectivity between SEA and East Asia and adds another route for regional traffic.
Echo and Bifrost
Echo and Bifrost form important transpacific connectivity routes linking SEA with North America. Echo connects Singapore and Indonesia towards North America, while Bifrost now connects Singapore, Indonesia, the Philippines and the US, with Mexico expected to be connected in 2026. The two systems were developed to increase transpacific capacity and route diversity, with Bifrost now operational and providing an alternative path for traffic between SEA and the US.
MIST
The Malaysia-India-Singapore Transit (MIST) cable system is an approximately 8,100 km submarine cable connecting Malaysia, India, Singapore and Thailand. The system has 12 fibre pairs and more than 216 Tbps of designed capacity. Commissioned in 2025, MIST provides a direct high-capacity connection between India and SEA and adds route diversity to the increasingly important India-Singapore connectivity corridor.
ADC
Asia Direct Cable (ADC) is a roughly 9,400 km system connecting Singapore with key markets including China, Japan, the Philippines, Vietnam and Thailand. The system entered service in 2024 and adds capacity and route diversity across East Asia and SEA.
SEA-ME-WE 6
SEA-ME-WE 6 is a major 19,000 km submarine optical cable system linking SEA with the Middle East and Western Europe. The system forms part of the broader SEA-ME-WE family of cables and is designed to provide high-capacity connectivity across the three regions.
IAX
India-Asia Xpress (IAX) is a subsea cable system linking India with Singapore and other Asian connectivity hubs. The system provides an additional route for traffic between India and SEA and strengthens the India-Singapore corridor. IAX is also part of the wider expansion of direct connectivity between Indian data centres and Southeast Asian digital hubs.
Developments and plans in SEA
Singapore
In July 2026, NEC signed a supply contract for the approximately 3,600 km India-Southeast Asia (I-2SEA) submarine cable system, connecting India with Malaysia and Singapore. The system is scheduled to enter service in 2029 and is being developed to support growing traffic from AI, cloud and hyperscale workloads. Tata Communications is among the consortium members. Separately, Tata Communications announced a $152 million investment to expand capacity along the India-Singapore corridor, including additional capacity on MIST and participation in a new Chennai-Singapore cable system targeted for service in the fourth quarter of 2029.
Indonesia
In July 2026, the Nongsa-Changi Cable (NCC), developed by Telin and BW Digital, landed at the Nongsa Digital Park in Batam. The approximately 50 km system has 24 fibre pairs and more than 1.6 Pbps of capacity, providing a direct connection between Batam and Singapore. It is one of two new Batam-Singapore systems being developed by the Telkom Group, alongside the Indonesia Singapore Cable System (INSICA).
Besides, MoraRepublic and HMN Tech completed factory acceptance testing for the wet-plant equipment of the Moratelindo International Cable System-3 (MIC-3). The system will connect Batam and Singapore through a 32-fibre-pair trunk with two branching units. Two additional reserved branching units are planned to support future extensions, including towards Jakarta.
Vietnam
Vietnam is also emerging as a focus for new regional connectivity. The MViSTA subsea cable, being developed by Vietnam’s Stavian Group, is planned to connect Vietnam with Thailand, Singapore and Malaysia. The system is being designed around connectivity between regional data centre hubs, including Singapore, Johor and Rayong, as well as a planned data centre campus in Vietnam. As of now, the project is progressing through planning and implementation, with the route being developed to provide an alternative regional path and reduce dependence on the main deep-water corridors of the South China Sea.
Thailand
Thailand is seeing investment in both existing and new international cable routes. In April 2026, Google’s TalayLink project received approval from the country’s telecom regulator. The proposed route will connect southern Thailand with Western Australia via Christmas Island and forms part of Google’s wider investment in cloud infrastructure in Thailand.
Existing infrastructure is also being upgraded. In June 2026, Symphony Communication selected Nokia to upgrade the Malaysia-Cambodia-Thailand (MCT) submarine cable. The upgrade uses Nokia’s PSE-6 coherent optics and is expected to increase capacity to up to 30 Tbps per fibre pair while reducing power consumption.
Thailand is also pursuing new regional routes. In September, Gulf Development and Singtel announced a strategic partnership to develop subsea connectivity between Thailand and Singapore, with the Vietnam-Thailand-Singapore (VTS) Cable System as the first project under the partnership. VTS is targeted to enter service by 2030. Separately, Thailand’s National Telecom has secured USTDA support for a feasibility study for the proposed Thailand-US (THUS) submarine cable. The proposed route would pass through Indonesia, Malaysia, the Philippines, Singapore and Vietnam, avoiding the South China Sea, but the project remains at the feasibility stage.
Malaysia
Malaysia is also strengthening its domestic subsea infrastructure. In July 2026, the Malaysian Communications and Multimedia Commission (MCMC) invited proposals for the Sambungan Kabel Dasar Laut MADANI (SALAM) project. The approximately 5,582 km system will connect Peninsular Malaysia, Sabah and Sarawak through four segments and 10 landing stations. The project is intended to increase network capacity and provide greater geographical diversity, while addressing the capacity limitations of the ageing 1Malaysia People’s Cable System cable system.
Faults, outages and route diversity
Subsea cable faults remain a key challenge, particularly in areas where multiple systems pass through the same waters. In August 2026, four international cables serving Vietnam suffered faults in quick succession, affecting the country’s international internet capacity. Traffic had to be shifted to other submarine and terrestrial routes.
The impact of a cable fault also depends on how quickly the damaged section can be repaired. Repairs require specialised cable vessels, while vessel availability, permits and access to affected waters can affect restoration timelines. ASEAN adopted enhanced guidelines in January 2026 to improve submarine cable repair and resilience, including by streamlining cross-border regulatory and permit processes.
Physical activity such as fishing, anchoring and dredging remains another source of damage, particularly in heavily trafficked waters such as the Straits of Malacca and Singapore. Intentional damage and cable theft are also a concern. Moreover, geopolitical considerations can further affect the planning and deployment of subsea cables. Routes passing through strategically sensitive or contested waters can face additional considerations related to installation, maintenance and route selection.
Future outlook
The next few years are likely to bring a more diverse subsea cable map across SEA. Data centre development will be an important factor in determining where this connectivity is needed. APAC’s data centre development pipeline reached 26.5 GW in the first half of 2026, with SEA accounting for around half of the region’s under-construction capacity. As new data centre clusters develop in markets beyond established hubs, cable routes are likely to increasingly follow these emerging centres of demand.
Cable build-out is consequently moving towards a network with more routes, more landing points and closer links between regional data centre markets. The challenge will be to ensure that this additional infrastructure translates into genuine route diversity rather than simply adding more capacity along the same corridors.
