Fun fact: In Alaska, the permafrost makes laying underground cables impractical. It's also not cost-effective to build overhead lines suspended from anchored poles. So to get broadband internet to rural interior communities, they use underwater fiber-optic lines laid in rivers.

Also mind-blowing is to see how much of the world uses underwater communications cables:

Those are images from this free online Submarine Cable Map, which is maintained by telecoms industry analyst TeleGeography. You can zoom in and out on the map and click on each cable to see which company owns it.

Lastly, none of us would be getting our undersea internet without something like this:

That's a fiber optic splice kit made by Ohio-based PMI Industries. It allows "a highly reliable, full ocean-depth splice with multiple levels of sealing protection."

PMI's splices are used, among other places, in the Alaska project.