>>1992742>>1992766If the cable physically breaks, the ships will literally fish for one or both ends of it with a grappling hook then resplice them to each other or a new length of cable.
If there's an internal fault, they will also grapple for it, fix it once on deck, and repair the multiple cover layers. Or, they can lower down a robot to work on it.
Neal Stephenson wrote a great nonfiction story about ocean cables in the 90s,
https://www.wired.com/1996/12/ffglass/There are a bunch of books about the original trans-Atlantic cable. They used the Great Eastern to hold the cable, and just like today, the cable broke multiple times and they had to fish for it and splice it back together.
