Compromised submarines cables and the consequences to internet?

I recently read an news that google want to build an submarines cables connecting to my country supposedly to increase overall speed and while i hope my government to never allow this kind of thing it made me curious about the actual security of submarines cables against man in the middle attacks.

I tried to google about that and only found that those links after look to many pages i could only regroup sparse information http://ift.tt/1BKTwbC http://ift.tt/1fFkPWz

I'm familiar with the concepts of encryption and i know that who do that will be able to intercept all http:// traffic but i also know https:// is not unbreakable and won't them be able to see all the handshakes happening between the parties to atleast do network analysis like i'm connecting to my vpn and they see my ip doing an handshake with the vpn ip and know that know i'm connecting to an vpn and be able to correlate my traffic when it leaves the vpn and much more?

So how bad would be to internet as whole actives man in the middles tapping submarine cables? I see that submarine cables are obviously interesting for many reasons to many country around the world and they tranpass international water space with no rules