Underneath the world's oceans, miles and miles of fiber optic-cables send packets of information from one location to the next, serving as the backbone of the internet as we know it. This infrastructure is delicate, too: Memorably, a 2022 volcanic eruption cut off the island of Tonga from web access for an extended period of time. Samanth Subramanian is the author of The Web Beneath the Waves: The Fragile Cables that Connect Our World, a recent book that explains, in detail, that the Internet is, and has never been, truly weightless or wireless. In fact, the system in place right now is pretty old school and resembles the telegraph cable network of yore. We talk to Subramanian about the strange contradictions of the undersea cable system, how much basic marine geography — like the Strait of Hormuz or the Suez Canal — informs where cables are laid, and how hard it is protect this vulnerable and vital infrastructure.