Its easy to forget how different things are in different parts of the world. Take Africa, for instance: A ship off the coast of Mombasa, didn't pull up their anchor properly. One of three (THREE!) undersea cables was cut. As a result, a significant amount of Internet service was slowed, or eliminated entirely, to several countries in East Africa. The repair is said to take two weeks (I'm guessing that may be a rosy estimate). In the meanwhile, the cost of diverting service to one of the other cables is expensive, so the Internet will just be slow.
I would assume a network outage of this magnitude in Europe or the US would see an overall slowdown of perhaps several minutes if cable based, milliseconds if land based. Ouch.
BBC: Ships Anchor slows down East African Web Connection