This long article from Wired in 1996, Mother Earth Mother Board [1], would answer your question. It is long, it took me more than a couple of hours to read, but it's also my all-time favourite article from any magazine, and whenever the topic of submarine cables comes up on Hacker News I often see this link.
[1] http://archive.wired.com/wired/archive/4.12/ffglass_pr.html
Edit: Also, it's written by Neal Stephenson for whatever that's worth.