Varna.info : Travel to Varna :

Istanbul to Varna

There are a number of ways to reach Varna from Istanbul. Turkey and Bulgaria being neighboring countries, the distance between these two cities Istanbul and Varna is just 259 km or 161 miles. There are planes, buses, trains and even a ferry service along the Black Sea Coast.

Flights Istanbul to Varna
There are a number of flights operating from Istanbul to Varna by different airlines. The rates range from 275 to 350 Euros for a one-way trip and around 685 Euros for a roundtrip. The total flying time is around 3 ½ hours, but there might be a stop over for about 6 hours in-between in some flights.
http://www.flybulgaria.bg/en/flights/turkey-bulgaria_tickets.html

Travel by Bus
There are buses departing from Istanbul to Varna everyday. It costs around 50 lev for a one-way trip. The travel time is around 7 hours. Some buses stop for food and restroom break. Istanbul has a large, modern bus depot from where more than 150 companies operate their services. Buses are very comfortable and are the best alternative to air travel.

Travel by Train
Trains take around 17 to 20 hours to reach Varna from Istanbul. This is of course much longer than it takes by bus. It costs 60 lev to around 90 lev with sleeper.
http://www.bdz.bg/

Travel By Ferry
There is a seasonal ferry service from Varna to Ukraine and Turkey during summer. The cost of a return trip is around 130 Euros. A company called Morova Turizm operates these ferries. For further details you can contact by telephone number 0212 248 2550.

People traveling these routes would come across name boards and signs written in the Cyrillic script. People used to the English alphabet might find things a little confusing. For instance, if you are looking for Varna, look for ‘Bapнa’ instead. That is how Varna is spelt. To know about more of these variations, you can pick up a card in the tourist bureau in Varna.