Nearly 99 percent of international internet traffic travels through fibre-optic cables laid across the ocean floor.

Demand for these submarine cables has reached an all-time high as cloud computing and artificial intelligence drive global data needs.

Only one company in the United States is capable of both manufacturing complete long-haul subsea telecom cable systems and laying them at sea.

That company is SubCom, based in Newington, New Hampshire.

Business Insider gained rare access to SubCom’s 73-year-old factory and boarded one of its multimillion-dollar cable-laying ships to examine how the firm operates.

At the New Hampshire facility, machines run around the clock processing thousands of miles of glass optical fibres. These fibres form the core of every subsea cable and can each carry hundreds of terabytes of data per second across oceans.

SubCom produces approximately 58,000 kilometres of undersea cable annually and is expanding capacity toward 77,000 kilometres by the end of 2026.

The company has built more than 200 underwater systems and in 2025 became the first to deploy one million kilometres of subsea cable.

Its customers include major technology firms such as Google, Meta, Amazon and Microsoft, which together account for a large share of the world’s data traffic and are racing to expand connections between their global data centres.

Submarine cables remain the backbone of international connectivity, even as satellite systems grow, because they offer higher capacity and lower latency for bulk data transfer.