Pacific Undersea Cables Explained: What They Carry, What Breaks Them and Why Islands Are Exposed
Undersea fiber-optic cables carry more than 95 percent of international data traffic, and about 99 percent by U.S. and UN estimates. For Pacific islands that rely on one or two cables, a single break can cut most internet and phone service, as Tonga found in 2019 and 2022. Most faults come from fishing gear and ship anchors, not sabotage. With the East Micronesia Cable finished in 2026, every Pacific Islands Forum member now has an undersea cable connection, but redundancy and repair capacity remain the open questions.
What do undersea cables do for Pacific islands?
Undersea telecommunications cables are the physical backbone of the internet. The Congressional Research Service reports that commercial cables carry about 99 percent of transoceanic digital communications, including voice, data and financial transactions, and that private companies and consortia operate more than 500 of them (Congressional Research Service). The International Telecommunication Union's Secretary-General gave the same 99 percent figure in 2024 (ITU). Australia's foreign ministry uses a more conservative estimate of more than 95 percent of international data traffic (DFAT).
For island governments, the cable is how hospitals reach specialists, banks settle payments, and emergency managers talk to partners abroad. The ICPC notes that satellites currently lack the bandwidth to match cables (ICPC, 2021). That's why a cable break matters more on a remote island than on a continent with many overland routes. ISPI's work on supply chain singularity describes the same pattern for shipping and fuel: one route in, one point of failure.
What breaks undersea cables?
Cable faults are routine. The International Cable Protection Committee (ICPC), an industry and government body, says about 150 to 200 faults occur worldwide each year, and that 70 to 80 percent are caused by accidental human activity, mainly commercial fishing and ships' anchors (ICPC). The ITU says that works out to about three cable repairs a week (ITU).
| Cause | Reported share or count | Source |
|---|---|---|
| Accidental human activity (fishing, anchors) | 70–80% of faults | ICPC |
| Ships' dragged anchors | About 30% of incidents, around 60 faults a year | ICPC on anchor damage |
| Natural hazards (earthquakes, landslides, volcanic activity) | Around 10% of faults | ICPC, 2024 |
| All causes | About 150–200 faults a year worldwide | ICPC |
Repairs are costly. The ICPC puts the average telecommunications cable repair at £500,000 to £1 million per incident (ICPC on anchor damage). In shallow water, where fishing and anchoring happen, cables are now routinely buried about 0.5 to 1 meter below the seabed, down to water depths of 1,000 to 1,500 meters (ICPC, 2024). Deliberate damage gets the headlines, and the Congressional Research Service records intentional cuts at landing sites in France in 2022, but the bulk of faults are accidents.
What happened when Tonga lost its cable?
Tonga has lost its international cable twice in recent years. In January 2019, a ship's dragged anchor damaged the cable and left the country with sharply limited internet and phone service for 12 days, at an estimated cost of US$200,000. Tongan police later concluded there was no foul play (RNZ).
On Jan. 15, 2022, the Hunga Tonga-Hunga Ha'apai eruption and tsunami severed the same link, which the BBC described as Tonga's sole source of reliable internet. Makeshift satellite services provided only limited communication while aid arrived. The repair ship Reliance spent 20 days replacing a 92-kilometer section of the 827-kilometer cable to Fiji, and service to the main island returned on Feb. 22, more than five weeks after the eruption (Reuters via The Guardian; BBC). Domestic cables to the outer islands still needed repair after that (BBC).
The lesson for planners is less about the volcano and more about dependence on one cable. Both outages fit the pattern the ICPC describes: rare natural disasters and common human accidents produce the same result when there's no second path (ICPC, 2024).
Is every Pacific Islands Forum member now connected?
Yes, as of 2026. In December 2021, Australia, Japan and the United States agreed with the Federated States of Micronesia, Kiribati and Nauru to fund a cable linking Kosrae, Nauru and Tarawa to the existing HANTRU-1 landing at Pohnpei, serving about 100,000 people (joint statement, Dec. 11, 2021). The cable contract was signed with NEC in June 2023, for a project estimated at AUD135 million (DFAT, June 6, 2023).
On Sept. 1, 2026, Australia announced that the 2,250-kilometer East Micronesia Cable was complete, that Australia had contributed about AUD65 million, and that all Pacific Islands Forum members are now connected to undersea telecommunications infrastructure for the first time (Australian Foreign Minister, Sept. 1, 2026; NEM Australasia). For background on the Forum itself, see ISPI's Pacific Islands Forum explainer and the Compact states hub.
Being connected isn't the same as being resilient. A country with one cable is still one fault away from a Tonga-style outage, which is why the policy conversation has moved to redundancy, repair and protection.
What are governments doing about cable resilience?
- Quad partnership. Australia, India, Japan and the United States announced the Quad Partnership for Cable Connectivity and Resilience in May 2023 (DFAT). Australia's contribution, the Cable Connectivity and Resilience Centre, launched in July 2024 with more than A$18 million over four years for technical assistance, research and government-industry dialogue (Australian Foreign Minister, July 29, 2024).
- ITU and ICPC advisory body. In November 2024 the two organizations formed the International Advisory Body for Submarine Cable Resilience, with 40 members including ministers, regulators and industry experts, drawn from countries ranging from small island states to major economies (ITU).
- U.S. policy debate. The Congressional Research Service found in 2023 that the United States had no comprehensive cable-protection strategy or designated lead federal agency, and set out options for Congress, including protection zones, route diversity and penalties for damage (Congressional Research Service).
What does this mean for Hawaii?
Hawaii's cable questions are both trans-Pacific and interisland. The state has worked to attract trans-Pacific cable landings, and its Hawai'i Subsea Middle Mile Program is funding a new subsea interisland fiber system, the first of a proposed two-part network. The 2024 report said the system was expected to be ready for service by late 2026 (University of Hawaii Act 231 broadband report, 2024).
For emergency managers, the practical question is what still works when a cable or landing station is out. ISPI's HI-06: Infrastructure Deficit and Island Resilience in Hawaii examines how single points of failure compound during disasters, and WP-06: Supply Chain Security and Community Resilience applies the same lens across island communities. More on this topic is collected in the supply chain and infrastructure hub and the emergency preparedness hub.
Frequently asked questions
How much international data travels by undersea cable?
Estimates range from more than 95 percent (DFAT) to about 99 percent of transoceanic communications (Congressional Research Service; ITU).
How often are undersea cables damaged?
About 150 to 200 faults a year worldwide, or roughly three repairs a week (ICPC; ITU).
Are most cable breaks sabotage?
No. The ICPC attributes 70 to 80 percent of faults to accidental human activity such as fishing and anchoring, and around 10 percent to natural hazards (ICPC; ICPC, 2024).
How long did Tonga go without its cable in 2022?
More than five weeks, from the Jan. 15 eruption until the repaired cable was handed back on Feb. 22 (BBC).
Sources
- Congressional Research Service, “Protection of Undersea Telecommunication Cables: Issues for Congress,” R47648, Aug. 7, 2023
- ITU, “Strengthening resilience of submarine cable networks is key to digital connectivity and economies,” press release, Nov. 29, 2024
- International Cable Protection Committee, “Media Enquiries & Frequently Asked Questions”
- International Cable Protection Committee, “Submarine Cable Protection and the Environment,” October 2024
- International Cable Protection Committee, “Submarine Cable Protection and the Environment,” March 2021
- International Cable Protection Committee, “Damage to Submarine Cables from Dragged Anchors”
- Mackenzie Smith, “‘No foul play’: Police report clears company at centre of Tonga cable cut,” RNZ, Nov. 28, 2019
- “Tonga volcano: Internet restored five weeks after eruption,” BBC News, Feb. 22, 2022
- Reuters, “Communications restored to Tonga a month after volcanic eruption and tsunami,” The Guardian, Feb. 22, 2022
- U.S. Department of State, “Joint Statement on Improving East Micronesia Telecommunications Connectivity,” Dec. 11, 2021
- Australian Department of Foreign Affairs and Trade, “Work to start on East Micronesia Cable following contract signing,” June 6, 2023
- Australian Minister for Foreign Affairs, “Landmark six-nation partnership delivers East Micronesia Cable,” Sept. 1, 2026
- Jamie Simpson, “East Micronesia Cable marks a major milestone for Pacific connectivity,” NEM Australasia, Sept. 2, 2026
- Australian Department of Foreign Affairs and Trade, “Cable Connectivity and Resilience Centre”
- Australian Minister for Foreign Affairs, “Launch of the Cable Connectivity and Resilience Centre,” July 29, 2024
- University of Hawaii, Act 231, SLH 2022, 2024 Broadband Infrastructure Report
- ISPI papers: HI-06, WP-06
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