Where are the undersea cables that link the Internet?
Most of the trans-continental Internet and phone traffic goes via submarine cables.
Here’s a great map of where all those cables are
There’s lots of little details on the map you can zoom in to see more.
The red number for each country is the dialling code.
At the bottom are two representations of the network latency (delay) from major hubs and the cable capacity with thicker lines meaning more bandwidth.
If you’re interested in a layman’s view of Internet infrastructure, check out Tubes: A journey to the center of the Internet available in paperback from May 2013 but now available and cheaper for Kindle.