Thinking back, I was first interested in submarine cables as a child.
Pictures of submarine cable repeaters reeling out over the stern of HMS Monarch featured in one of my favourite books “How it Works – The Telephone”. This also had cross-sections of city streets showing the pipes and cables beneath.
I was always fascinated by what could not be seen, and the thought of pencil thin cables travelling for thousands of miles between continents, miles below the ocean surface, was no different.
For the UK, a pretty definitive maps of submarine cables are held by Kingfisher (their cable awareness maps) at http://www.kis-orca.eu/ They have pdf downloads, and a very comprehensive interactive map with switchable layers for power cables, oil pipelines, wind turbines, and so on.
The interactive map is here http://www.kis-orca.eu/map
A Google earth version is here: http://www.justmagic.com/GoogleMaps_SubmarineCables.html