Let that sync in

What makes the internet possible? The short answer: miles of fibreoptic cables that lie on the ocean floor. Who builds them? Who tends to them? How is the map of these links changing? In a new book, Subramanian chases the cables around the world, talking to people who mend them and depots that ship them out; untangling the intense corporate power grabs and geopolitics that dictate how and where a new one is laid. ‘The internet is really very territorial, and vulnerable,’ he says

- Gowri S

There are about 900,000 miles of undersea cables lying on our ocean floors, holding filaments often as thin as a human hair. Together, these cables transmit 95% of all international data, and form the physical web that makes the internet possible.

Each such cord has at its heart the actual glass fibres. Protecting these are layers of steel wire, covered in copper wire, covered in polymer fabric (for final waterproofing). The whole assemblage then simply sits on the ocean floor.

"For the longest time, there were about 100 to 120 cable cuts a year, nearly all of them accidental. There would be a geological event or a shipping vessel would chuck its anchor overboard, and it would land on a cord and cut it," says author Samanth Subramanian, 44 (formerly a journalist with HT's business paper, Mint).

Today, countries have taken to patrolling their deep-sea lines. (India, incidentally, has 17; regulated by the government and owned and maintained by communications companies such as Tata and Reliance, in frequent collaboration with global tech giants such as Meta and Alphabet.)

Subramanian's new book traces such cords around the world. The Web Beneath the Waves traces elements of risk, geopolitical tension and corporate power grabs. "In recent years, various countries have been suspected of deliberately cutting their rivals' cords," he says.

How often does that happen? What else did he learn, in his two-and-a-half years researching the subject?

Excerpts from an interview.

You've written about fish, geopolitics, war-ravaged Sri Lanka. How did this book on undersea cables come about?