Digging through underwater history – the Marmaray Tunnel Project
photo by electropod

Given Istanbul’s a crammed city, it seems obvious to dig underground for infrastructure solutions. But, as the underwater Bosphorus tunnel proves, below the ground is just as cluttered as above.

Yes, there’s something going on under Istanbul’s waters. The world’s deepest undersea-immersed tube tunnel currently lies dormant under the Bosphorus Strait. Marmaray is the grand title given to this underwater rail transport project, a combination of the ‘Sea of Marmara’, which lies south of the project site, and the Turkish word for rail, ray. And while the tube tunnel was completed back in 2008, it’s still yet to grace Istanbul with a grand opening. Yes, there was more than just mud lurking underneath.

The project quickly became a constructer’s nightmare… and an archaeologist’s dream. Breaking the ground back in 2004, it’s been a long wait to unearth all the historical artifacts buried in the mud.

Digging the European-side entrance tunnel revealed a trove of byzantine-era treasures – the city’s largest harbor, traces of Constantine the Great’s city wall, and the remains of several ships, including what appears to the only ancient or early medieval gallery ever discovered.

Not interesting enough? Surely even a non-history buff can fathom excitement at the discovery of Istanbul’s oldest settlement at a ripe old age of 6000BC. Seems it was popular site to live, even back in prehistoric times.

But not everyone is excited about the discoveries that caused a four-year delay and some 500million Turkish Lira. The Turkish Prime Minister sees Istanbul’s residents as more important than ‘archaeological stuff’ (his words, not mine).

The tunnel is just the Asian-European connection point of a high-capacity 76km railway system. As one of the world’s major transportation infrastructure projects at present, it also involves three new underground stations at Yenikapı, Sirkeci, and Üsküdar, and the renewal or renovation of 37 surface stations and tracks. Plus, a third track will be added to accommodate future long-distance/high-speed passenger trains. The usage of rail transportation in Istanbul is predicted to rise from 3.6% to 27.7%. And with Istanbul’s congested traffic and smoggy skyline, a public transport system is sorely needed.

But experts say the discoveries are priceless heritage artifacts for “humanity’s history.”

With all that hidden history below, it seems Istanbul’s development projects could find themselves in a constant fight between The People and The Past. Who will win the war?

It’s certainly not stopping the Turkish Prime Minister’s future visions for Istanbul’s infrastructure. By 2023, residents should be able to drive underwater if the construction of the projected underwater highway is ever realized.

Better bring your trowel

What’s the tunnel’s claim to fame? Yes, deeper and longer tunnels exist already. What’s different, however, is the v Tunnel’s 1.4km central section made from earthquake-proof submerged tubes. Each of the 11 tubes is about 130m (430ft) and weighs up to 18,000 tons. Unlike the tunnel’s bored-rock entrances, the central tubes are connected with flexible joints that can withstand earthquake shakes without breaking. This is important, seeing the tunnel lies just near the North Anatolian Fault, which has over a 50% chance of a strong quake in the next 30 years. At 55-60m underwater, it’ll be deepest of its kind.

Meet the author


After leaving Australia in 2003, Casey's path landed her in Istanbul for a summer stint only. Once addicted to Istanbul's eccentricity and charm, Casey failed to find reason to leave six years later. An avid traveller of sorts, Casey spent most of her time roaming across Europe and the Middle East looking for adventure and cultural experiences. Now a freelance editor and writer working from Madrid, Casey spends her days finding the words to excite the inner traveller in everyone.