https://www2.telegeography.com/submarine-cable-faqs-frequent...
"Don't these cables ever break? Yes! Cable faults are common. On average, there are over 100 each year.
You rarely hear about these cable faults because most companies that use cables follow a “safety in numbers” approach to usage, spreading their networks' capacity over multiple cables so that if one breaks, their network will run smoothly over other cables while service is restored on the damaged one.
Accidents like fishing vessels and ships dragging anchors account for two-thirds of all cable faults. Environmental factors like earthquakes also contribute to damage. Less commonly, underwater components can fail. Deliberate sabotage and shark bites are exceedingly rare. "