The Matsu Islands are an archipelago of 36 islands in the East China Sea, alongside the southeastern coast of mainland China. The islands have been administered since 1949 by Taiwan, part of a larger set of outlying islands administered by Taiwan, which includes the Kinmen and Penghu Islands, which all lie in the Taiwan Strait.

The Matsu Islands are connected to Taiwan’s main island by two submarine cables — Taima No.2, Taima No.3, and soon Taima No.4. The Taiwan Strait is a shallow body of water, with an average depth of 70m. The submarine cables that lie on this seafloor are vulnerable to damage from ship-based activity, like being snagged by fishing equipment or anchors. But these particular cables have been remarkably unlucky. Between 2018 and 2022, the submarine cables between Taiwan and the Matsu Islands were cut 27 times, and there have been four major outages in the three years from 2023 to 2025.