NTT Group Company Weighs Building New Ship for Undersea Cables
By Rurika Tanaka and Kyoko Hariya, Nikkei Asia
December 13, 2025
TOKYO — NTT World Engineering Marine is considering building a new vessel to lay submarine cables, it has been learned, amid a push for the important communications arteries to be tended to by domestic companies.
The Japanese marine tech company is considering building another vessel comparable to the Subaru, its biggest cable-laying vessel, within the next 10 years.
Built in 1999, the Subaru measures 124 meters in length, with gross tonnage of 9,557 metric tons. But the ship is getting old and is set to leave port in Yokohama again in January for repairs.
Its utilization rate was just over 60% in fiscal 2024 based on vessel working days.
NTT-WE Marine has laid over 51,000 kilometers of subsea cable, including both domestic and international. Beyond laying cables, it also performs ocean surveys to inform cable route selection and handles maintenance for a total of 11 cable systems, most of which are owned by the NTT group.
Submarine cables are vital infrastructure to economic security, helping to keep up with rapid growth in communications demand with the rise of video content and artificial intelligence. Right now, the total length of the roughly 570 undersea cables in use worldwide comes to approximately 1.48 million kilometers, enough to circle the globe 37 times.
As an island nation, 99% of Japan's international communications pass through these cables. This means that any damage to them would have a significant impact on economic and social activity.
Undersea cable is manufactured by three major companies that together have a 90% market share. Those are France's Alcatel Submarine Networks, U.S.-based SubCom, and Japan's NEC. Of those, NEC has a share of just over 20%, which is small, but still larger than that of HMN Technologies, a Chinese cable maker that was once a part of Huawei Technologies.
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