Subsea Cables and Australian Data Centres: Why Landing Stations Matter

Why subsea cables matter to data centre buyers

Australia is an island continent, so almost all of its international internet and data traffic travels on fibre optic cables laid across the sea floor. The Australian Communications and Media Authority (ACMA) notes that submarine cables carry the bulk of Australia's international voice and data traffic. Satellites play a part, but they carry a small share by comparison.

If your business serves customers in Asia or the United States, replicates data to an overseas cloud region, or simply relies on fast access to global services, the cables that land closest to your data centre matter. They affect how quickly traffic reaches the rest of the world, how many independent paths you can use, and how well you ride out a cable fault. This guide explains where the cables land, why landing stations matter, and what to ask before you choose a site.

Where Australia's international cables land

Most of Australia's international cables come ashore in a small number of places:

• Sydney. Sydney has the largest group of cables. Systems that land there include the Southern Cross Cable Network and Southern Cross NEXT to the United States, Hawaiki to the United States, the Australia Japan Cable, JGA South towards Guam and Japan, Tasman Global Access to New Zealand, PIPE Pacific Cable 1 to Guam, the Coral Sea Cable System to Papua New Guinea and Solomon Islands, and INDIGO Central, which links Sydney with Perth.

• Perth. Perth is Australia's main gateway to the Indian Ocean and South-East Asia. Cables landing there include SEA-ME-WE 3, the Australia–Singapore Cable, INDIGO West to Singapore and Indonesia, and the Oman Australia Cable towards the Middle East.

• Sunshine Coast. JGA South also lands at Maroochydore on the Sunshine Coast, which gave Queensland its own direct international cable route.

• Darwin. Darwin is linked to Port Hedland and offshore sites by the domestic North-West Cable System, and new international systems towards South-East Asia, such as Asia Connect Cable-1, have been announced.

Domestic subsea links matter too. SUBCO's SMAP cable, which links Sydney, Melbourne, Adelaide and Perth by sea, was declared ready for service in June 2026. Our Sydney–Melbourne fibre guide covers how domestic routes affect two-site designs.

New international systems are announced regularly, so treat any list as a snapshot and check current status with carriers before you rely on a particular cable.

What a landing station is and why it matters

A cable landing station is the building where a subsea cable comes ashore and connects to the land network. From there, terrestrial fibre (often called backhaul) carries traffic to the data centres where carriers, clouds and customers meet.

For buyers, the landing station matters for three reasons:

• Distance. Every extra kilometre of fibre adds latency. Light in fibre travels at about 5 microseconds per kilometre, so each extra 100 km of path adds roughly 1 millisecond of round-trip time. A data centre with a short, direct path to the landing station starts with a small advantage.

• Choice. Data centres that act as interconnection hubs near landing points usually have more carriers on site, which makes it easier to buy capacity on several different cables.

• Resilience. If all your international traffic depends on one cable, or on several cables that share one landing station or one backhaul path, a single fault can cut you off.

In practice, most businesses do not connect to a landing station directly. They buy international capacity from a carrier inside a well-connected data centre and link to it with cross-connects. What matters is how many cables and carriers that data centre can reach, and how physically separate those paths are.

Latency and resilience implications

Latency to overseas markets is set mostly by distance. From Australia's east coast, cables head north towards Asia or east across the Pacific towards the United States. From Perth, cables head north-west to Singapore and west towards the Middle East. That is why Perth is often a good fit for workloads that serve South-East Asia, while Sydney has the widest choice of routes across the Pacific. Our Perth buyer's guide looks at the Western Australian market in more detail.

Resilience comes down to diversity. Cables can be damaged by ship anchors, fishing gear and natural events, and repairs at sea can take time. To lower that risk, ACMA has declared three submarine cable protection zones under Schedule 3A of the Telecommunications Act 1997: Northern Sydney, Southern Sydney and Perth. Activities that could damage cables, such as some types of fishing and anchoring, are prohibited or restricted inside these zones. Protection zones reduce risk, but they do not remove it, so your design should still assume a cable can fail.

Good international resilience usually means:

• Services on at least two different cable systems, ideally landing at different stations.

• Backhaul paths from each landing station that do not share the same trench or building entry.

• A clear understanding of how your carrier reroutes traffic after a cable fault, and what latency applies on the backup path.

Choosing a data centre with the cables in mind

When you shortlist sites, ask how each facility connects to international capacity, not just which carriers are listed on a brochure. Use the DChunt map and coverage page to see where facilities sit, then compare local options on our Sydney, Perth, Brisbane and Darwin pages. Our connectivity choices guide explains the main service types, from internet transit to private links, and the provider directory lets you compare operators.

Questions to ask data centres and carriers

• Which subsea cable systems can we reach from this facility, and through which carriers?

• Which landing stations do those cables use, and how far is the backhaul path to this building?

• If we buy two international services, do they use different cable systems and different landing stations?

• Where do the backhaul paths share any trench, duct or building entry?

• How is traffic rerouted after a subsea cable fault, and what latency should we expect on the backup route?

• What are the fault response and restoration commitments in the service level agreement?

DChunt is independent and does not resell data centre space or network services. Our free assessment can help you match your international connectivity needs to the right facilities and cities.