Australia's undersea cable infrastructure is entering a new phase of strategic redundancy. SUBCO, the domestically owned cable builder, has moved to harden the resilience of its Sydney-Melbourne corridor by splitting that critical segment across independent subsea and terrestrial paths, a move designed to protect customers from the sorts of catastrophic outages that have historically crippled international data flows.
Traditionally, customers needing redundant connectivity between Australian cities have been forced to engineer their own protection, juggling contracts with multiple providers while hoping their chosen routes were genuinely geographically separate. SUBCO is characterising the terrestrial investment as additional diversity across high-traffic corridors, linking it to its broader plans for multiple independent paths between major digital hubs. This arrangement shifts that burden from customer to infrastructure owner.
SMAP is expected to provide 400Tbps of undersea fibre capacity linking Australia's east and west coasts primarily via a route tracing from Sydney down the east coast to Melbourne and on to Perth through the Southern Ocean with a spur linking to Adelaide, supported by additional terrestrial capacity linking Sydney and Melbourne. The $750-million-class investment represents the largest capacity upgrade to Australia's transcontinental backbone in nearly a quarter-century.
The cable company's strategy reflects a fundamental shift in how Australia approaches digital infrastructure. Rather than leaving redundancy to market forces, SUBCO is bundling diverse assets into a single integrated offering. Coupled with its shareholding in the existing Indigo Central subsea route from Sydney to Perth, the company now operates what amounts to a multi-path corridor immune to single-point failures affecting either undersea or terrestrial segments.
AI demand driving urgent expansion
What drives such investment is the imminent explosion in data demand. Hyperscalers and neoclouds are looking to deploy 3GW of AI factories in Australia between now and 2028, which is going to need between 75Tb-150Tb of international capacity to deliver those tokens to the world, with any future system with a 2029 or 2030 ready-for-service date simply not working. That urgency has shaped SUBCO's timeline for its new APX East cable, a sovereign-owned connection to San Diego scheduled for late 2028.
The rationale for SUBCO's aggressive investment schedule runs counter to conventional thinking about infrastructure lead times. The company has effectively bet that Australia's window for capturing AI-driven compute investment closes quickly; miss this moment, and the continent risks becoming a data-processing consumer rather than a hub. APX-East is an all deepwater system between Sydney and California, that reduces permitting risk, allowing an accelerated installation and completion, with the company noting that international connectivity at AI scale will be a critical enabler for Australia's aspirations to become a leader in the AI world.
The political economy here deserves attention. APX East is Australia's first sovereign-owned international hypercable reducing reliance on US hyperscalers for Australian connectivity needs. That matters because data transit increasingly carries strategic weight. Control over how information moves between continents is control over what information moves, under what terms, with whose oversight. A domestically owned cable means Australian interests shape those terms.
Why this matters beyond commerce
Submarine cables carry over 95 per cent of international data traffic globally. They are not optional infrastructure; they are economic and strategic necessities. Australia is connected via more than ten cables but with a handful of primary landing points in Perth and Sydney, creating a concentration risk that geopolitical instability or deliberate sabotage could exploit.
The emphasis on diversity, resilience, and domestic ownership is sensible policy disguised as commercial competition. SUBCO's moves align with Australia's broader recognition that the Cable Connectivity and Resilience Centre is tasked with protecting the critical undersea telecommunications cables throughout the Indo-Pacific region from deliberate interference from malicious actors, or accidental damage. When infrastructure becomes a strategic asset, public interest and private return converge.
SUBCO's announcement is ultimately about preparing Australia for an era when data is as vital to national capability as physical energy or military hardware. The company is betting that capacity, reliability, and sovereignty matter enough to justify enormous capital expense on infrastructure that competes directly against cheaper routes through third-country landing points. Whether that bet proves correct will depend partly on how aggressively Australia moves to capture AI-driven compute investment, and partly on whether geopolitical risks to more congested routes continue to mount.