Underwater tunnel set to connect Europe to Asia by 2028

It will be 6.5km-long

But whilst some of talk of tunnels between London and New York might seem like the stuff of science fiction, a very real mega-construction project is currently underway linking two of the world's continents - and it should be operational before the end of the decade.

The Great Istanbul Tunnel is being constructed to link Europe and Asia by crossing the Bopshorus River, which splits the Turkish capital between the two continents.

At 6.5km-long, it will be the world's longest underwater tunnel once completed.

When it does open in 2028 - all things going according to plan - the tunnel is set to cater to 1.3 million passengers.

In May this year, Türkiye’s transport and infrastructure minister Adil Karaismailoğlu gave an update on the project, confirming the timeline and some additional details.

The Great Istanbul Tunnel will feature three levels, two of which will be for cars and the other one will be for a rail system.

The tunnel will have a diameter of 19m, will sit 110m below sea level and will connect the highways between Istanbul’s three airports: Istanbul Atatürk Airport, Sabiha Gökçen Airport, Istanbul Airport, and the nine rail lines of the Istanbul Metro.

The railway will feature 13 stations, accommodating 70,000 passengers per hour in one direction. It will also connect with 11 other railways, and relieve the strain from Istanbul's Metrobus line, allowing it to function at optimal capacity.

According to Karaismailoğlu, it will take 40 minutes to make it across the Bosphorus by train.

The tunnel is being built following projections that daily crossings between the European and Asian sides of Istanbul will exceed three million in the future, a 50 per cent increase on current levels.