Black Sea

The Black Sea was a marginal, mostly enclosed, sea roughly situated between Europe and Asia. (TV: War of the Sontarans)

The sea either bordered or was proximate to Russia, Turkey, Kurdistan, Georgia and Ukraine. (PROSE: Trading Futures) In particular, the coastal city of Istanbul was bisected by the Bosphorus strait, which ran between the the Black Sea and the Sea of Marmara. (PROSE: Byzantium!)

History
Shortly after the TARDIS materialised in Thrace, Barbara Wright observed a sunset over the Black Sea. (PROSE: Byzantium!)

President Felix Mather and Anji Kapoor once flew over the Black Sea. (PROSE: Trading Futures)

The Black Sea appeared on General Logan's map of the eastern hemisphere in an alternate 1855. (TV: War of the Sontarans)

Alternate timelines
During the Year That Never Was, 100,000 Toclafane rockets were constructed at a shipyard spanning across Russia from the Black Sea to the Bering Strait. (TV: Last of the Time Lords)