The 6 billion euro undersea tunnel connecting Spain & Morocco


A major project resurfaces: the marine tunnel connecting Morocco and Spain through the Strait of Gibraltar.

Report by Sophie Gatward-Wicks

View of Strait of Gibraltar looking across to Morocco

From 1930 – 2030

The idea of building a bridge connecting Spain to Morocco was first born in 1930, when a joint committee between the two countries investigated the feasibility of linking the two continents. Spain initially suggested constructing a modern tunnel beneath the Strait of Gibraltar, however, a significant challenge emerged when engineers hired by the Spanish government found that the material beneath the Strait was extremely hard rock, making tunnelling impossible with the technology available over 90 years ago.

Then in 1979, a meeting between the late King Hassan II of Morocco and former King Juan Carlos of Spain, resulted in the formation of a joint committee and the creation of two specialised entities: Morocco’s National Company for the Studies of the Strait of Gibraltar (SNED), and a Spanish company for the study of fixed communication across the Strait of Gibraltar (SECEGSA). The tunnel project would deliver a high-speed railway link between Casablanca in Morocco and Madrid in Spain, which could reduce travel time between the two cities to just five-and-a-half hours.

Map of Spain and Morocco

Decades later, and with technologies even further advanced, the project has resurfaced as a viable effort, with aims to be completed ahead of 2030, when Spain, Portugal and Morocco will jointly host the Fifa World Cup of football. Various other organisations, such as the European Commission, the Euro-Mediterranean Partnership, the Centre for Transport Studies for the Western Mediterranean, the Arab Maghreb Union, and the United Nations Economic and Social Council (ECOSOC) have all expressed interest in the project due to its potential benefits for the international community.

The Benefits

Europe is Africa’s largest trade partner, with over $160bn worth of goods exported every year, (about 36% of Africa’s total exports), a trade which has never been more important than today, with the ongoing instabilities in the East of Europe. Though facilitating cross-border movement is not all about the trade. A high speed connection between the two continents would promote tourism, cultural exchange, labor exchange and increase Spain’s importance and influence, as well as Africa’s, contributing to the prosperity and cohesion of both regions on a global scale. Sustainability is also an important benefit of high-speed rail travel, as it remains the most environmentally friendly mode of transport compared to air or road travel. Promoting rail travel between Spain and Morocco would contribute to reducing carbon emissions, and support Europe’s environmental and climate goals.

Image of a high speed train

The Challenges

One of the project’s main challenges involves overcoming the fact that the shortest route between the two continents, spanning approximately 14 kilometers, is also the deepest, with sea depths in some areas reaching up to 900 metres (3,000 ft) below sea level. Consequently, the most likely location for the tunnel to be built is the Camarinal Threshold, the shallowest point of the Strait of Gibraltar, with a maximum depth of 300 metres (984 ft) below sea level. Another concern is the seismic challenges that are present in the Strait of Gibraltar due to heightened tectonic activity resulting from the convergence of the Eurasian and African plates, as well as the Alboran sub-plate. There are also two deep Quaternary clay channels in the middle of the Strait which would add complexity to construction.

The website reported: “The Strait Tunnel of Gibraltar is a “high complexity” project, and has no equal on the planet. Nevertheless, the engineers involved are confident that the technological progress in the tunnel industry over the past decade will open up new perspectives for the material implementation of the project. They can also remove the last doubts about the technical feasibility of the work.”

surveying by the sea

SNED reported that, together with SECEGSA, they have conducted a total of 44 oceanographic surveys. These surveys encompassed over 10,000 km of geophysical features using seismic reflection techniques, more than 5,000 km of side sonar surveys, and the collection of 5,000 seabed samples. Several wells have also been drilled in locations including Bologna and Tarifa in Spain, as well as near Tangier in Morocco.

As for the latest technical details of the project, stated recently: “The planned tunnel will have a total length of 38.7 km, of which 27.8 km is underwater. This will connect two railway terminals. Both tunnels are 42 km apart. The tunnel will be designed to transport thousands of passengers and tons of goods every day.”

The Cost 

In February 2023, after a high-level bilateral meeting between Spain and Morocco, the Spanish government announced a €2.3 million funding package for a joint Spanish-Moroccan design and planning committee for the tunnel. SNED and SECEGSA are jointly responsible for managing the financing of the proposed tunnel project, although an official cost has not been announced, recent estimates suggest that the total construction cost will be approximately 6 billion euros.

Image of possible tunnel configuration.