For people interested in this, I can recommend Neal Stephensons Wired feature from the 90's. As you'd expect from Stephenson, it's crazy long. It describes his travels documenting the laying of an early submarine Internet cable.
It's really weird thinking about, that every time I swipe around that map on my phone, what I see is sent over some of those exact cables from the other side of the world.
it has been speculated that sharks are attracted to the magnetic field created by the high voltage carried through the cables, which resembles those created by fish.
http://archive.wired.com/wired/archive/4.12/ffglass.html