What to know about submarine cable cuts behind East Africa internet outage

What to know about submarine cable cuts behind East Africa internet outage

The submarine cable cutter "Nessie II" is being used between the islands of Rügen and Hiddensee to lay empty pipes 1.80 to 3.50 deep in the seabed for the broadband connection to Hiddensee.(Photo by BERND WUSTNECK / dpa-Zentralbild / dpa Picture-Alliance via AFP)

Since Sunday, slow internet speeds have been experienced in East and South Africa after damages to major subsea cables supplying broadband across the continent through the Red Sea.

Users of both fibre and mobile broadband are confronting outages and while there is little information on the nature of the damage or its cause, internet service providers (ISPs) servicing the East African region say they are working to minimise interruption as they await the full restoration of the cables.

It is reported that the damage has affected at least two of the major subsea gateways which supply connectivity to telecommunications networks in the East and Southern Africa regions.


Subsea or submarine communications cables are cables laid on the sea and ocean bed that use fibre-optic technology to transmit data such as telephone and internet traffic to provide telecommunications links across the world's continents.

Unlike satellite technology, which transmits communication signals to points that are not wired, subsea cables are tucked down in the water using special cable layer ships.

Nearer to the shore, they are buried under the beach for protection.

These cables are therefore the main force powering internet connectivity across the world’s continents and their damage can cause widespread internet outages.

The U.S. telecoms market research company TeleGeography estimates that there are over 570 undersea cables around the world as of early 2024, and it is reported that submarine cables account for 90 per cent of Africa’s internet needs.

Almost all of the subsea cables servicing the world are privately owned by telecom operators or investors.

Many of them are funded by internet giants such as Google, Meta, Microsoft, and Amazon, according to a 2016 report by TeleGeography.


For the current outage being experienced in East Africa, it is said there are three cuts in three of the submarine cables powering the region’s connectivity, while another cable system is faulty.

Ben Roberts, the Group Chief Technology and Innovation Officer for Liquid Telecom on Sunday reported faults in the Eastern Africa Submarine Cable System (EASSy) and the Seacom cables.

EASSy is a 10,000-kilometre submarine cable system along the east and south coasts of Africa.

It is one of the highest-capacity systems serving the continent, linking South Africa with Sudan through landing points in Mozambique, Madagascar, the Comoros, Tanzania, Kenya, Somalia and Djibouti.

The South Africa-based Seacom, Africa's first broadband submarine cable system, meanwhile runs along the continent's Southern coasts.

It is a 17,000-kilometre cable providing Djibouti, Kenya, Tanzania, Mozambique, and South Africa with connectivity.

Roberts on Sunday pointed out that two other key submarine cables in the Red Sea; the Europe India Gateway (EIG) and the Asia-Africa-Europe 1 (AAE-1), also had unrepaired cuts.

The 15,000-kilometre EIG links the U.K., Portugal, Gibraltar, Monaco, France, Libya, Egypt, Saudi Arabia, Djibouti, Oman, United Arab Emirates, and India, while the AAE-1 connects Southeast Asia to Europe via Egypt, over a 25,000-kilometre distance.

In most cases, large telecom companies and ISPs rely on multiple cable systems so that if one experiences issues, they can reroute traffic to ensure uninterrupted service.

This, therefore, explains the magnitude of having several subsea networks damaged.

Kenya’s Communications Authority says there was a deep-sea fibre cut at the Mtunzini teleport station in South Africa, affecting the Seacom and EASSy subsea cable channels.

CA on Monday said it is closely monitoring the situation to ensure incoming and outbound internet connectivity while also directing service providers to secure alternative routes for their traffic.

"The East Africa Marine System (TEAMS) cable, which has not been affected by the cut, is currently being utilized for local traffic flow while redundancy on the South Africa route has been activated to minimize the impact," it added.


Submarine cable faults have previously been attributed to human activities like fishing and harbouring in shallow waters near the seashore, as well as natural hazards such as earthquakes and landslides.

In March, a suspected underwater rock slid off the coast of Cote d’Ivoire, interrupting several submarine cables serving the West African region.

In February 2012, three submarine cables were cut in the Red Sea due to a ship dragging its anchor.

Other factors such as the firing of missiles, especially in the Red Sea with the ongoing war in Yemen, have been reported to contribute to submarine cable damages.

The Yemeni government has accused Houthi rebels of targeting the subsea cables in the Red Sea, something the rebels have denied.

The Houthis instead blame British and US military units operating in the area for the damage.


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