[ThinkBeat]

Is it safe to assume that there exists a lot of cables that we are not supposed to know about or at least that are not public and not on such amps?

I have long been thinking that the NSA must have some high capacity "black" cables to help the surveillance of the internet. Primarily to capture data, sending all the captured data back through the public internet would be counterproductive.

A 5eye private subsea network?

I would assume other countries have some for similar reasons

[dmvdoug]

Well, SOSUS had cables that people knew fed into landing stations on the coast but what exactly they were for remained classified until like the 1980s. So those are literally classified government cables. If you mean secret Internet cables, I have no clue, but hey, history teacher had a history answer so… hi. :)