SEAX-1

SEAX-1: A regional submarine cable linking Indonesia, Malaysia, and Singapore

SEAX-1 is a submarine telecommunications cable system operated by SEAX, connecting Batam in Indonesia, Mersing in Malaysia, and Tanah Merah in Singapore. With a total length of 250 kilometers, it serves as a regional link within Southeast Asia, facilitating data transfer between these three countries. The cable was recorded as ready for service in 2018 according to GeoCables data, and it remains listed as in service. What makes SEAX-1 particularly interesting is the absence of publicly disclosed technical specifications such as design capacity, fiber pair count, and supplier details. This lack of transparency is not uncommon for smaller regional cables, but it limits the ability to analyze its full technical capabilities and market positioning. Additionally, latency measurements suggest that real-world performance is influenced by factors beyond the cable itself, highlighting the complexity of assessing submarine cable efficiency.

Quick facts

System Name	SEAX-1
Length	250 km
Ready for Service (RFS) Year	2018 (GeoCables database; no conflicting data found)
Owner	SEAX
Status	In service
Design Capacity	Not disclosed
Fiber Pairs	Not disclosed
Supplier	Not disclosed
Technology	Not disclosed
Landing Points	Batam (Indonesia), Mersing (Malaysia), Tanah Merah (Singapore)

Show SEAX-1 on the interactive cable map

Route

SEAX-1 connects three landing points: Batam, Mersing, and Tanah Merah. Batam, an industrial hub in Indonesia, is a major landing site for numerous submarine cables, including the Apricot and Matrix Cable System. Mersing, located on Malaysia’s east coast, is similarly a landing point for other regional systems like the Asia-America Gateway (AAG) Cable System and Sistem Kabel Rakyat 1Malaysia (SKR1M). Tanah Merah in Singapore, a key node in global telecommunications, links SEAX-1 to the broader international network, hosting cables such as the Australia-Singapore Cable (ASC). The corridor covered by SEAX-1 is geographically compact, reflecting its role as a regional connector rather than a transcontinental system. Its short length of 250 kilometers minimizes latency and makes it well-suited for intra-regional traffic.

Why it was built and what it carries

SEAX-1 was built to enhance connectivity between Indonesia, Malaysia, and Singapore, three economically interdependent nations within Southeast Asia. The cable likely supports data traffic for enterprise, consumer internet, and mobile services, though specific traffic types are not publicly documented. Its role as a regional cable suggests that it complements larger systems that provide global connectivity, rather than competing directly with them.

History: what can be established

SEAX-1 was recorded as ready for service in 2018 according to GeoCables data. No conflicting dates have been identified in industry sources, so this appears to be a reliable figure. The absence of detailed historical documentation makes it difficult to assess the planning, construction, and commissioning phases of the cable.

Capacity and technology

Publicly available sources do not disclose SEAX-1’s design capacity, fiber pair count, or the technology used in its construction. Without operator documentation, it is impossible to determine whether the cable employs cutting-edge transmission technologies such as wavelength division multiplexing (WDM) or advanced optical amplifiers. This lack of information is typical for smaller regional systems, which often operate with less public scrutiny than larger transoceanic cables.

Latency: the physics

The theoretical one-way light propagation latency for SEAX-1 is approximately 1.2 milliseconds over its 250-kilometer length, yielding a round-trip time (RTT) floor of 2.5 milliseconds. However, real-world latency is always higher due to additional factors such as land tails, terminal equipment, and routing. GeoCables live measurements provide insights into end-to-end latency but must be interpreted cautiously. For example, the reported minimum latency of 0.8 milliseconds between Batam and Mersing is below the physical floor of 2.5 milliseconds, indicating a measurement artifact likely caused by rate-limited ICMP replies from intermediate routers. The average latency of 51.4 milliseconds for the same path reflects the broader internet routing and not the cable's intrinsic performance. Similarly, latency measurements from global locations such as Sao Paulo and Tbilisi to Mersing include terrestrial and other submarine cable segments, making them unsuitable for assessing SEAX-1 directly.

Redundancy: what happens if it breaks

SEAX-1 operates in a corridor with significant redundancy. Batam alone hosts over a dozen submarine cables, including the Indonesia Global Gateway (IGG) System and Palapa Ring West, which could reroute traffic in the event of a failure. Mersing and Tanah Merah are similarly well-connected, with systems like the Asia Submarine-cable Express (ASE) and Australia-Singapore Cable (ASC) providing alternative paths. Standard industry practices for submarine cable repair, including the deployment of specialized cable ships, would apply to SEAX-1 in the event of a fault.

Bottom line

• SEAX-1 is a 250-kilometer regional submarine cable linking Batam (Indonesia), Mersing (Malaysia), and Tanah Merah (Singapore).
• Owned by SEAX, it was recorded as ready for service in 2018 and remains listed as in service.
• Technical details such as design capacity, fiber pairs, supplier, and technology are not publicly disclosed.
• Theoretical latency over the wet segment is 2.5 milliseconds RTT, but real-world measurements reflect broader internet routing.
• Redundancy is strong due to the presence of numerous alternative cables at all three landing points.