Meta announces Petal, the first transoceanic subsea cable to carry a full petabit per second

Meta announced Petal this month, a subsea cable system it describes as the first transoceanic cable ever built to carry a full petabit per second of data — roughly double the capacity of the fastest transoceanic cables in service today. The cable will stretch about 7,000 kilometers (4,300 miles), connecting landing points in the United States and France, with French telecom Orange handling the cable's arrival on that end. Meta is building the system with NEC, which specializes in subsea cable systems, and Sumitomo Electric Industries, which will produce the fiber itself.

A petabit per second is a difficult number to make concrete. Meta's own comparison: that much bandwidth is roughly enough capacity for 75% of the world's population to stream music simultaneously. It's also worth putting the milestone in context of just how much of the internet actually depends on cables like this one — subsea cables carry approximately 99% of all intercontinental internet traffic, meaning the undersea infrastructure most users never think about is functionally the backbone of the global internet, far more than satellites or any other long-haul technology.

The technical breakthrough enabling Petal's capacity jump is multi-core fiber, a technology that packs multiple independent data-carrying cores into a single strand of fiber optic cable, rather than relying on a single core per strand as most existing transoceanic systems do. Meta says this is the first deployment of multi-core fiber at true transoceanic scale, allowing the cable to roughly double throughput without a proportional increase in the power or physical infrastructure needed to run it — a meaningful distinction, since power and physical bulk have historically been hard limits on how much capacity a single subsea cable route can support.

Meta frames Petal as the largest single generational jump in transoceanic subsea cable capacity ever built, and the company has skin in this game well beyond one cable: it has now invested in more than 20 subsea cable projects worldwide. That scale of investment reflects a broader shift among the largest cloud and AI companies, which increasingly build and co-own the physical network infrastructure connecting their data centers rather than purchasing capacity from traditional telecom carriers — giving them direct control over the bandwidth their AI training and inference workloads increasingly depend on moving between continents.

Petal is expected to enter service in 2029, a multi-year timeline typical for transoceanic cable projects, which require specialized cable-laying ships, seabed surveying, and regulatory approval across every jurisdiction the cable passes through or lands in. For now, the announcement is a signal of where subsea cable technology is headed rather than a capacity boost users will feel immediately — but the multi-core fiber approach, if it performs as designed at this scale, is likely to become the template for the next generation of transoceanic builds well beyond Meta's own network.