Samanth Subramanian on the Undersea Cables That Keep the Internet Alive

In this episode of Odd Lots, hosts Tracey Alloway and Joe Weisenthal dive deep into the hidden physical infrastructure that powers the global internet: undersea fiber optic cables. With guest Samanth Subramanian, author of 'The Web Beneath the Waves,' they explore how these cables—some dating back over a century—form the backbone of digital communication, connecting continents and enabling everything from AI training to financial markets. Subramanian reveals that while the cables resemble shipping lanes on maps, their placement is driven by geography, economic activity, and geopolitical risk. He discusses the shift from government and telecom consortiums to dominant tech giants like Google, Meta, Amazon, and Microsoft funding and owning most new cables, raising concerns about internet bifurcation and data sovereignty. Despite the rise of satellite internet, the episode underscores that fiber optics remain irreplaceable due to bandwidth limitations. The hosts reflect on the fragility of this system, from accidental cuts by fishing vessels to deliberate sabotage threats, especially in choke points like the Strait of Hormuz and the Suez Canal. The conversation concludes with a sense of awe at the technological marvel of light-based data transmission and the paradox of a digital world built on ancient, fragile, and increasingly concentrated infrastructure. Key takeaways include: (1) The internet is not 'wireless'—it relies on physical undersea cables, not satellites; (2) Big tech companies now control the majority of new cable projects, creating potential for internet fragmentation; (3) Geopolitical tensions are increasing threats to cable security, with military patrols and alternate routes being developed; (4) Redundancy exists but is not foolproof, as seen in Tonga’s internet blackout after a volcanic eruption; (5) The AI boom is accelerating demand for more cables, reversing earlier fears of overcapacity; (6) Military and private corporate networks use dedicated cables, separate from the public internet; (7) Repairing cables remains a labor-intensive, low-tech process involving grapnel hooks and on-board labs; (8) China’s HMN, a Huawei spinoff, is a key alternative cable provider, though sanctions limit its global use. The episode ends with a call to appreciate the physical reality behind our digital lives.