Caspian Sea

The Caspian Sea was a large inland sea on Earth. According to Yuri Kerenski, it was technically more of a lake than a sea. Dagestan was located by the Caspian Sea (TV: The Waters of Mars) as was Tashkent. (AUDIO: The Memory Cheats)

The Year That Never Was
In an alternate timeline during the Year That Never Was, poisoned the sea. (TV: Last of the Time Lords) Martha Jones later visited it during her travels around the globe. (PROSE: The Story of Martha)

Behind the scenes

 * The "Sea" which Tehraun overlooks, though only partially named on the map in Survivors of the Flux, is the Caspian Sea.