So the deep-sea lines that let you watch cat videos from the other side of the world are heavily reinforced to ensure that internet outages are the exception rather than the rule. Essentially that means a lot of steel reinforcing, a whole heap of polymer shrouding, and a dash of copper shielding. Get through all of that and lurking there, just in the middle, are a few precious glass fibers that carry your data.
It might seem like overkill, but it really is worth it: When one was damaged in Myanmar earlier this year, the country's bandwidth instantly plummeted. More here.