How do foreign warships pass through Turkey?

Recently, there were reports of Russian naval ships based out of the Black Sea traveling to Syria. This led me to ask, how the hell do countries that have naval ships in the Black Sea get in and out of the Black Sea, given that Turkey controls the only entrance/exit (the Bosphorus and Dardanelles)?

The answer is in the 1936 Montreaux Convention Regarding the Regime of the Straits. This site summarizes the convention:

1. The aim of the Montreux Convention is to regulate the passage of civilian and military ships through the Turkish Straits.
2. The term Turkish Straits covers the Dardanelles, Marmara Sea and the Bosporus.
3. The Convention makes a clear differentiation between Black Sea countries (Turkey, Bulgaria, Romania, Ukraine, Russia, Georgia) and non-Black Sea countries.
4. Merchant vessels enjoy a total freedom of passage through the Turkish Straits.  Turkish Straits Vessel Traffic Services Centre regulates the passages according to the Maritime Traffic Regulations for the Turkish Straits dated 1998.
5. The Black Sea Countries;
   • cannot pass warships solely designed to carry airplanes through Turkish Straits.
   • can pass submarines if they are joining their base in the Black Sea for the first time after their construction or purchase, or if they are returning from a repair in dockyards outside the Black Sea.
   • can pass their warships through Turkish Straits by notifying Turkey through diplomatic channels 8 days before the passage.
6. The Non Black Sea Countries;
   • cannot pass warships solely designed to carry airplanes through Turkish Straits.
   • cannot pass submarines.
   • can pass warships, but the aggregate displacement of the foreign warships in the Black Sea may not exceed 45.000 tons.
   • cannot hold their ships in the Black Sea longer than 21 days.
   • cannot have more than 9 ships in the Black Sea at the same time
   • can pass their warships through Turkish Straits by notifying Turkey through diplomatic channels 15 days before the passage.