When I think of globe-spanning internet signals, my mind goes to the skies. But only a small percentage of internet traffic is bouncing between satellites. The vast majority, 95% or more, is traveling through surprisingly thin cables at the bottom of the ocean. 

As you can imagine, those cables are not easy to install, maintain, or repair when things go awry—which happens more and more frequently as both climate change and geopolitical tensions make the ocean a more volatile environment. Stephen Shankland explores those complexities, as well as the surprisingly interesting history of these high-speed cables, in this CNET feature. 

These cables, only about as thick as a garden hose, are high-tech marvels. The fastest, the newly completed transatlantic cable called Amitié and funded by Microsoft, Meta and others, can carry 400 terabits of data per second. That’s 400,000 times faster than your home broadband if you’re lucky enough to have high-end gigabit service.

And yet subsea cables are low-tech, too, coated in tar and unspooled by ships employing basically the same process used in the 1850s to lay the first transatlantic telegraph cable. SubCom, a subsea-cable maker based in New Jersey, evolved from a rope manufacturer with a factory next to a deep-water port for easy loading onto ships.