Doing a map of a flight from Sines, to Bermuda, to Charleston airports:

* http://www.gcmap.com/mapui?P=LPSI-TXKF-KCHS

The (great circle) route is straight through the Azores.

* https://en.wikipedia.org/wiki/Great-circle_navigation

Whomever made the map for the diagram just drew a straight line from Portugal to Bermuda, which works for a flat surface, but in the real world the world is round, so the shortest distance is often curved (as it appears on a 2D projection).

However this site shows the cable travelling south of the Azores:

* https://www.fiberatlantic.com/system/n5OE4

Not really south, it's just a bit north: Ponta Delgada - Latitude: 37.7333 Longitude: -25.6667. Lisbon - Latitude 38.71667 Longitude -9.13333. It is the exclusive economic zones of Portugal that are in the path of the cable: https://en.m.wikipedia.org/wiki/Exclusive_economic_zone_of_P...