Protecting Submarine Cables: Two Submarine Telecommunication Cables Break off the Shetland Coast

The detailed map can be viewed here.

Written by Dr Youri van Logchem

On 20 October 2022, a submarine telecommunication cable running between the Orkney Islands and the Shetland Islands snapped. In its wake, a major incident was declared by the Scottish police, as the Shetland Islands were almost completely cut-off from the outside world as a result. A few weeks earlier, another telecommunications cable laying off the coast of Shetland Islands broke; this cable connects the United Kingdom and Denmark, making a landfall in the Faroe Islands (reportedly, this same cable was damaged in the previous month of September). Hence, in relatively short succession, two cable segments of the same cable system, SHEFA-2, were damaged. SHEFA-2 is a 1000 kilometres long submarine cable system, connecting via different cable segments the United Kingdom to the Danish Faroe Islands. After the breaking of the cable connecting the Orkney Islands and the Shetland Islands, connectivity was relatively quickly restored, as it took approximately one day to make the necessary repairs. As to the cause of the break of the cables, several theories were initially floating around on the Internet, one of which was that the cables were wilfully damaged, because the breaking of two connecting cables in such short succession would be too much of a coincidence. Although the breaking of two adjacent cables is rare indeed, an alternative explanation, and a less nefarious one at that, would be that the breaking of the cables is tied to either the harsher weather conditions or extensive fishing activity within the North Sea.

Irrespective of the cause lying behind the breaking of these two submarine cables, events such as these bring the issue of the protection of submarine telecommunication cables, due to their significance, into the limelight.

Most international communications do not run via satellites high up in space, but rather via underwater cables, which are placed on or buried in the seabed, usually in waters deeper than 1500 meters. They form the backbone of international communications, with them being used in about 97% of the world’s communications.[i] However, submarine telecommunication cables are susceptible to damage from natural disasters, hydrocarbon exploitation, shipping activities, rough weather, but also targeted attacks, including from terrorists, which all can be counted among the activities that carry the potential of breaking or injuring submarine cables. One of the main threats is dredging and anchoring by fishers, however. Once a submarine telecommunication cable is damaged, this can lead to a serious disruption in communications, which lays bare the need for its quick repair. The impact of when cables are damaged was vividly illustrated by when communications in the Shetland Islands were significantly disrupted for some time due to the damage caused to a cable lying off their coast. Although after the cable connecting the Orkney Islands and the Shetland Islands broke, connectivity was restored within a day or so, when seen in a broader light not all can be considered right with the protection of submarine telecommunication cables, not least from a legal point of view. An example is that when after a volcanic eruption in January 2022 the sole cable on which the island State of Tonga is virtually dependent for maintaining its international communications snapped, Tonga found itself virtually isolated from the world almost completely for close to a month.

Quite regularly, submarine telecommunication cables pass through different maritime areas, also of more than one coastal State. Although this is not the case for the second cable that broke off the coast of the Shetland Islands (i.e., the one connecting the Orkney Islands and the Shetland Islands), the earlier damaged cable connecting the Shetland Islands to the Faroe Islands is an example of a cable lying between two different coastal States; i.e., Denmark and the United Kingdom. Depending on the submarine cable segment involved, the applicable international legal rules and the extent of coastal state authority may vary. Submarine cables may be located in a maritime area that is under the sovereignty of a coastal state (e.g., the territorial sea), an area that is within functional coastal state jurisdiction (i.e. the exclusive economic zone (EEZ), and the continental shelf), or an area beyond coastal State jurisdiction (i.e., the high seas).[ii] In a nutshell, beyond the territorial sea (and archipelagic waters) where coastal State enjoy sovereignty, the 1982 Law of the Sea Convention (LOSC) provides that all states have the right to lay, maintain, and repair transit submarine cables (Articles 58(1), 79(1), and 87(1)(c) of the LOSC).

Within the LOSC, there are some specific provisions dealing with the protection of submarine cables, especially with respect to the EEZ and continental shelf, whose roots can be retraced to the 1884 International Convention for the Protection of Submarine Telegraph Cables and the 1958 Geneva Convention on the High Seas. More specifically, the relevant provisions can be found in Articles 113-115 of the LOSC.[iii] One obligation flowing from Article 114 of the LOSC is that coastal States must make laws and regulations, providing that when during the laying or repairing of a new submarine cable, a break or injury is caused to a submarine cable already in place, the owner of the new cable is liable for damages caused.

While cable protection is addressed in the LOSC, some weaknesses are laid bare upon closer analysis. One such weakness, being more general in nature, is that the LOSC does not obligate coastal States to adopt laws and regulations to protect submarine cables within their territory, including in port or in the territorial sea.[iv] In the light of that cables are particularly vulnerable in shallow(er) waters, it is very much desirable that coastal States criminalise the intentional, or through negligence, damaging of submarine cables located within their territory. Connected to this, often, the source of difficulties arising concerning cable protection can be retraced to the coastal States themselves. In this vein, whereas in certain States a domestic legal framework is completely absent, in others it may be inadequate or antiquated.[v] Although comparatively more infrequent, cable breaks are not isolated to shallow(er) waters, as is also illustrated by the breaking of the cable that connects the Shetland Islands to the Faroe Islands. Beyond the territorial sea, submarine cables are more regularly placed directly on the seabed, rather than buried in the subsoil, rendering them vulnerable to damage from competing activities, such as anchoring and dredging. Another difficulty is that despite the obligations the LOSC places on coastal States by way of Articles 113-115 of the LOSC, requiring States to introduce domestic legislation on certain issues surrounding cable protection in the EEZ and continental shelf, several of them have not done this.

A lack of awareness as to the significance of submarine cables continues to be a factor lying behind cable protection not always attracting the legal attention it requires from coastal States.[vi] Parallel to this, activities related to submarine cables are undertaken mainly by private actors and not States themselves. However, this does not mean that States have no role to play in regard of this critical infrastructure, as they, among others, retain the responsibility to ensure a submarine cable network is sufficiently resilient, meets safety and security requirements, and that cable repairs can be made as swiftly as possible.

Cable repairs is another problematic issue, as certain States around the globe have regulations and laws on the books that significantly complicate undertaking the necessary repair work by the submarine cable industry after a cable has been damaged.[vii] But that is another story, one that is beyond the scope of this blog. 

[i] Youri van Logchem, ‘International Relations and Defence Committee, corrected oral evidence: UNCLOS: fit for purpose in the 21st century?’ Wednesday 3 November 2021, available at

[ii] Youri van Logchem, ‘Submarine Telecommunication Cables in Disputed Maritime Areas’ (2014) 45(1) Ocean Development & International law, pp. 108-111.

[iii] Douglas Burnett et al., ‘Overview of the International Legal Regime Governing Submarine Cables’ in Douglas Burnett et al. (eds.), Submarine Cables: The Handbook of Law and Policy (Maritinus Nijhoff, 2014), pp. 84-87.

[iv] Ibid., p. 84.

[v] Robert Wargo and Tara Davenport, ‘Protecting Cables from Competing Uses’, in Douglas Burnett et al. (eds.), Submarine Cables: The Handbook of Law and Policy (Maritinus Nijhoff, 2014), p. 263.

[vi] Ibid., pp. 263-264.

[vii] Van Logchem, supra note ii, p. 113.