There is a convenient daily train from Bucharest to Istanbul that's called the Bosphor Express. It connects these two vibrant cities providing amazing scenery that you'd never want to miss.
The Bosphor Express stops at Dimitrovgrad, where it connects with the Sofia - Istanbul Express. This provides an additional option for reaching Istanbul from Sofia, the capital of Bulgaria. With these train connections, you can easily explore multiple destinations in the region.
During summer season, a daily night train also connects Istanbul with Bucharest. The train from Bucharest to Istanbul ends at Istanbul Halkali station, from here you can take a metro/Marmaray train to the city centre and under the Bosphorus to the Asian side. Make sure to have Turkish Lira notes beforehand, as most metro-ticket machines do not take bank cards.
To ensure a good journey, it is important to make a reservation for these trains. Reservations are compulsory and can be conveniently made at the train station. This allows you to secure your seat and plan your trip accordingly.
To plan your itinerary and check the schedules for the Bucharest-Istanbul and Sofia-Istanbul routes, you can refer to this website for additional timetable information. This will help you to plan your journey and make the most of your time.
In addition to the provided schedule, it's recommended to visit the official website of the respective railway company for more details and up-to-date information. These websites offer information about the train services, including any changes or updates that may affect your travel plans.