https://motherboard.vice.com/en_us/article/j5kj7g/this-is-how-the-internet-crosses-the-ocean

Inside an unassuming brick building in the windswept seaside town of West Jutland, Denmark, lies the beating heart of the internet. Well, one of them.

Underneath the Atlantic Ocean, a small web of cables connect the internet in Europe to North America, and in West Jutland, one of those cables arrives back on land. These cables cross 30,500 kilometers so that Danish computers can reach Google’s servers in South Carolina and vice versa. It’s easy to overlook the fact that our internet still relies on so much physical infrastructure, but a visit with Keld Sørensen, the marine maintenance manager of this facility, will quickly remind you that we’re all literally connected through wires sitting on the ocean floor.