Taiwan Penghu Kinmen Matsu No.3 (TPKM3)

Overview

The Taiwan Penghu Kinmen Matsu No. 3 (TPKM3) is a domestic submarine cable system in Taiwan, spanning approximately 510 kilometers. It was commissioned in 2013 and is owned by Chunghwa Telecom. Designed to connect Taiwan's main island with the Penghu, Kinmen, and Matsu archipelagos, TPKM3 plays a critical role in ensuring digital connectivity for these remote island communities. Without such infrastructure, these islands would face significant digital isolation, impacting communication, commerce, and access to essential services.

While TPKM3 is not distinguished by cutting-edge specifications, its importance lies in its role as a critical link for island connectivity. Its strategic placement in geopolitically sensitive and heavily trafficked waters has made it vulnerable to damage, whether accidental or deliberate. The cable's significance extends beyond its technical attributes, serving as a vital lifeline for communities often at risk of disconnection due to external factors.

Route and Landings

TPKM3 connects multiple points across Taiwan's main island and its outlying archipelagos. On the main island, the cable lands at Tainan and Taoyuan, key urban centers with substantial populations and economic activity. From there, it extends to the Penghu islands, landing at Magong, Huxi Township, and Xiyu Township. In Kinmen, the cable reaches Jincheng Township, the administrative center of the island group. For the Matsu archipelago, TPKM3 connects to Nangan, Beigan, Dongyin, and Xiju.

The cable's configuration resembles a "star," with the main island serving as the central hub and the outlying islands as its spokes. This design ensures that multiple island communities benefit from the same infrastructure, making it an efficient solution for domestic connectivity. The route crosses the Taiwan Strait, a region characterized by busy maritime traffic and geopolitical sensitivity, which increases the risks of anchor damage and other disruptions. The cable's presence is vital for these islands, which rely on it for internet access, digital communication, and integration with Taiwan's mainland economy.

Ownership and History

TPKM3 is owned and operated by Chunghwa Telecom, Taiwan's largest telecommunications provider. Since its launch in 2013, the cable has been a cornerstone of domestic connectivity, linking Taiwan's main island to its remote territories. Its importance has been underscored by incidents that have highlighted the vulnerability of Taiwan's subsea infrastructure.

One such incident occurred in February 2025, when the TPKM3 cable was damaged near Penghu. The vessel Hong Tai 58, flagged in Togo and crewed by Chinese nationals, was identified as being responsible for severing the line. This event was part of a broader pattern of cable damage around Taiwan, including the high-profile severing of the main cables to the Matsu islands in early 2023. These incidents have raised concerns about the security of Taiwan's submarine cable network, which is critical for the digital resilience of its island communities.

While redundancy exists through other TPKM cables, microwave links, and satellite backups, repair times remain a significant challenge. The Matsu islands, for instance, faced over 50 days of internet outage in 2023 due to cable damage. These events have sparked discussions about the need for enhanced monitoring and protection of subsea infrastructure in Taiwan's waters.

What Our Measurements Show

Our live monitoring of TPKM3 reveals key insights into its operational performance and the challenges it faces. The cable is divided into five measured corridors, with the best round-trip time (RTT) recorded at 260 milliseconds and an average RTT of 270 milliseconds. These metrics indicate a stable connection under normal circumstances, but disruptions can lead to significant latency increases, particularly when island communities switch to backup systems like microwave links or satellite connectivity.

Proximity to busy maritime routes and geopolitically sensitive areas amplifies the risks to TPKM3. Anchor dragging, vessel stops, and drift patterns are critical factors that our probes monitor to assess potential threats to the cable. Correlated risks, such as simultaneous damage to multiple cables serving the same region, further underscore the fragility of island connectivity. Recovery times remain a pressing issue, as demonstrated by the extended outage in Matsu in 2023, where residents faced weeks of disconnection before repairs could be completed.

TPKM3 exemplifies the broader challenges of ensuring reliable subsea infrastructure in regions with high geopolitical and environmental risks. Its performance and resilience are not just technical matters but vital concerns for the communities it serves, making ongoing monitoring and risk mitigation essential.