Marmaray

In November 2005, the men digging the European end of a railway tunnel under the Bosphorus, at Yenikapı, found a harbour. It was the Harbour of Theodosius, built in the late fourth century as Constantinople's main port for trade, used until the eleventh, then silted up, turned to fields and built over. The Istanbul Archaeological Museums dug the site until 2013 and brought up 37 ships of the fifth to the eleventh centuries — the largest group of medieval wrecks ever found in one place, among them the first Byzantine galleys ever excavated — and with them the oldest evidence of settlement in the city, from around 6000 BC. The railway waited: the project opened four years late, largely because of what its station site turned out to hold.

What it was building is the Marmaray, a 76.6-kilometre commuter line from Halkalı in Europe to Gebze in Asia. Two old suburban railways, one along each shore of the Sea of Marmara, were rebuilt with a third track and joined under the strait — the first standard-gauge rail link between the two continents, since every earlier one ran through Russia on its broad gauge. The tunnel opened on 29 October 2013; the whole line, on 12 March 2019.

It is a working railway, not an excursion: a card at the turnstile, a train every quarter of an hour, 43 stations. But between Sirkeci and Üsküdar it runs 60 metres below sea level, and the crossing from one continent to the other takes four minutes.

The trains are E32000s, built by Hyundai Rotem with its Turkish partner Eurotem for this line alone: 440 cars in five- and ten-car sets, walk-through from one end to the other, good for 105 km/h. The line was designed for 75,000 passengers an hour in each direction.

From Halkalı the line runs east towards the old city along the Sea of Marmara, on the route of the first railway out of Istanbul — the fifteen kilometres to Halkalı were laid in 1870–71, before the extension to Sirkeci — through Yeşilköy, Ataköy and Bakırköy. At Kazlıçeşme it drops into the tunnel, and the next stretch is 13.6 kilometres underground: Yenikapı, then Sirkeci beneath the Orient Express terminus, then the strait.

The crossing is an immersed tube: eleven concrete-and-steel sections, the largest 135 metres long and up to 18,000 tonnes, sunk to the seabed, joined and covered with earth. The deepest point is 60.46 metres below sea level, under 55 metres of water. The North Anatolian Fault lies about 18 km away, so the ground was grouted 24 metres down to stop it liquefying, each section is watertight on its own, and floodgates at the joints can close. Four minutes after Sirkeci the train is at Üsküdar.

It surfaces at Ayrılıkçeşmesi and joins the railway of 1873 along the Asian shore — Söğütlüçeşme, Bostancı, Kartal, Pendik, Tuzla — to Gebze, over the boundary in Kocaeli province.

Sharing the tube

The Marmaray is not the only traffic in the tunnel. Three high-speed trains a day each way now run through it between Halkalı and Ankara or Karaman, passing Sirkeci and Üsküdar without stopping, and on 7 November 2019 the first freight train from China to Europe came through — a journey from China to Turkey cut from a month to twelve days.

Trains run every 15 minutes from end to end, from about six in the morning until eleven at night. Between Ataköy and Pendik extra trains run in between, so the busiest middle of the line — including the crossing — has a train about every seven or eight minutes. There is nothing to reserve: you walk on. Times below are TCDD's own, as of September 2026.

Halkalı → Gebze

Gebze → Halkalı

The whole run takes 1 hour 48 minutes, and the crossing itself — Sirkeci to Üsküdar — four. TCDD's timetable also lists two later trains each way — 23:28 and 23:58 from Halkalı, 23:20 and 23:50 from Gebze — that do not run every day.

The operator's own times, and a station-to-station journey planner, are on TCDD Taşımacılık's Marmaray pages (opens in a new tab).

There are no tickets to book. You pay at the turnstile with an Istanbulkart, the city's transport card, or a Türkiye Kart; a single-use Marmaray card is sold for the whole line, with no refund if you ride less of it. The fare depends on how many stations you travel. The turnstile takes the highest fare possible from your station, and at your destination a refund machine by the exit gives back the difference — so touch your card on it before you leave, or pay for the whole line.

Since February 2026 the fare runs from 34 TL for up to seven stations to 74.70 TL for the full 36–43, end to end. One card can pay for several people, but only one refund is made per card — see TCDD's fare and card rules (opens in a new tab). Fares checked in September 2026.

A pass does not cover the Marmaray. Turkey is in the Interrail and Eurail area, but Interrail's table of railway companies lists Marmaray trains among the trains a pass excludes on TCDD Taşımacılık, and its Türkiye page says so directly: passes are not valid on Marmaray trains. The whole line costs 74.70 TL on an Istanbulkart, so buy the card.

A pass earns its keep on the long trains out of Istanbul: the high-speed lines to Ankara and Konya, and the night trains east except the Turistik Doğu Ekspresi, which the table also excludes. Several of the Ankara trains leave from Halkalı and run through the Marmaray tunnel themselves; those are YHT trains, which a pass covers. Checked against Interrail's railway-companies table, last updated 28 August 2026, and its Türkiye page, in September 2026.

The Marmaray links the sights on either side of the water, and most of what follows is a short walk from a station exit: the land walls near Kazlıçeşme, the museums above Sirkeci, the mosque by the landing at Üsküdar. Gebze, at the far end, is a separate trip, a little over an hour from Sirkeci.

The line crosses the whole city, so the question is which side to wake up on. On the European side the historic peninsula around Sirkeci puts you on top of the station and within walking distance of the museums; on the Asian side Üsküdar has the Marmaray and the ferries leaving from the same waterfront.

Either works for the other: from Sirkeci to Üsküdar is one stop and four minutes.