Australia’s vulnerable submarine cables, by Jessica Woodall at The Australian Strategic Policy Institute

Scattered across the ocean floor in intricate webs, submarine cables transfer high data volumes between onshore nodes. Five main international cables connect Australia to cyberspace and global voice networks. They carry 99% of Australia’s total internet traffic, dwarfing the capacity of satellites. Submarine cables are vital to our communications, economic prosperity, and national security. They also tend to break. A lot.


In most regions of the world this isn’t unexpected, or particularly worrying. Submarine cables aren’t much thicker than a garden hose and for the most part sit untethered and unprotected on the sea floor. Inadvertent breakages from ship anchors, nets and natural phenomena such as undersea earthquakes occur frequently, averaging at least one a week. To mitigate this risk, international agreements between cable operating companies are extensive, repair ships are quickly deployed and traffic is usually rerouted through other cables.

Unfortunately, the situation for Australia is more complicated. Sitting in the Southern Hemisphere, we’re largely isolated from the busy network of Transatlantic and North Asian Cable lines. We’re also unable to use overland fibre optic cables from other countries, leaving us reliant upon just a handful of international undersea cables.