İDO (İstanbul Deniz Otobüsleri)

Who they are

İDO — İstanbul Deniz Otobüsleri, literally "İstanbul Sea Buses" — is the public fast-ferry and car-ferry operator that links İstanbul to the southern shore of the Sea of Marmara. Founded in the 1980s to relieve pressure on İstanbul's road bridges and urban motorways, the company has grown into one of Turkey's most heavily used ferry networks, carrying millions of passengers a year across the inland sea that separates the European city from the Bursa region and the Marmara hinterland.

İDO operates two distinct service types: high-speed passenger catamarans (the deniz otobüsleri, or "sea buses") that serve commuters and fast-travel passengers, and larger ro-ro car ferries that carry private vehicles and their occupants on the same Marmara crossings. The combination makes İDO equally useful for the daily commuter, the family driving to Bursa for the weekend, and the traveller connecting to Anatolia without fighting İstanbul traffic.

Network and routes

İDO's primary axis runs from İstanbul's European and Asian ferry terminals south-west to Mudanya, the port for Bursa — Turkey's fourth-largest city and a destination in its own right for its historic mosques, silk bazaars and nearby Uludağ ski resort. From Mudanya the journey into central Bursa takes a further 30–40 minutes by road or public transport. A separate terminal at Güzelyalı (also for Bursa) serves the eastern Bursa shore.

The İstanbul–Yalova service connects the city to the Yalova resort area on the southern Marmara shore, a popular weekend destination for İstanbullus, with onward connections toward Bursa, Çanakkale and the thermal spas of the region.

İstanbul–Bandırma is the longest İDO crossing and the most strategically useful for travellers: from Bandırma, a direct train runs to İzmir, cutting many hours off the otherwise long journey south from İstanbul. The sea crossing takes around two hours and is a classic alternative to the coastal motorway.

Fleet and on board

İDO's seabus fleet consists of large fast catamarans designed for high passenger volume rather than luxury — these are commuter vessels first and foremost. Seating is aircraft-style with reclining seats, air conditioning and large windows. There is typically an on-board café selling tea, coffee, snacks and light meals; on longer crossings the canteen-style catering is a genuine option for a meal.

The car ferry fleet operates ro-ro vessels: vehicles drive on at the stern and off at the bow. Passenger facilities on car ferries are more spacious, with open deck areas that make the crossing pleasant in fine weather. The two-hour Marmara crossing on a clear day offers fine views of the Sea of Marmara and, on the İstanbul departure, the city's skyline receding behind the vessel.

All İDO routes are domestic Turkish services — no passport or visa formalities apply.

Booking and tips

İDO tickets can be booked through the İDO website and app, at port ticket machines, or at staffed ticket offices. The system accepts credit cards and the İstanbul transport card (İstanbulkart) on some routes.

For car ferry sailings, particularly on Friday evenings and before public holidays, book car spaces days in advance — demand is high and spaces sell out. Passenger seats are more readily available but can also fill on the busiest holiday departures.

Arrive at the terminal at least 30 minutes before departure for passenger travel, and 45–60 minutes if you are loading a vehicle. İDO terminals on the European side are at Yenikapı (the main hub); Asian-side departures operate from Pendik and Bostancı depending on the route.

The Marmara crossing is domestic, so no passport is needed — a standard Turkish identity document or travel document for foreign visitors suffices.