As the Léon Thévenin eased into Cape Town port last month, Shuru Arendse was ready to rush home to his family. He had a month off and a laundry list of to-do’s: fix a leaky tap, patch a hole in the roof, take his two children to the trampoline park.

But halfway through Arendse’s leave, there was a phone call: An undersea internet cable off Angola was malfunctioning. The Thévenin, the only cable repair ship permanently stationed in Africa, was heading off to fix it, and Arendse was needed. He is a cable jointer — one of a handful of people on the continent who know how to splice cables together.

Working on an internet cable repair ship is grueling but rewarding — and never more important than in today’s hyperconnected world, a handful of the Thévenin’s crew members told Rest of World. This report is based on three years of observations and two weeks onboard the ship.

“I’m trying to save a country from losing its data or communication,” Arendse said. “I love the challenge of it; it’s never the same.”

Data races from people’s devices over terrestrial networks to exchange points and data centers, where it is routed and sometimes sent abroad through massive undersea internet cables. Some of these stretch thousands of kilometers across ocean floors before surfacing at distant cable-landing stations and rejoining land-based internet.

With the artificial intelligence boom, the infrastructure through which data travels has taken on more importance, Steve Song, senior director of infrastructure mapping at the nonprofit Internet Society, told Rest of World.