Black Sea which are largely responsible for regional precipitation inputs and influence Mediterranean Sea Surface Temperatures (SST's). The relative strength of these systems also limits the amount of cold air arriving from northern regions during winter. Other influencing factors include the regional topography, as depressions and storms systems arriving from the Mediterranean are funneled through the low land around the Bosphorus, Pontic and Caucasus mountain ranges acting as wave guides, limiting the speed and paths of cyclones passing through the region. There are some islands in the Black sea that belong to Bulgaria, Romania, Turkey, and Ukraine: The Black Sea is connected
Caspian Sea the Volga, is connected by important shipping canals with the Don River (and thus the Black Sea) and with the Baltic Sea, with branch canals to Northern Dvina and to the White Sea. Another Caspian tributary, the Kuma River, is connected by an irrigation canal with the Don basin as well. Several scheduled ferry services (including train ferries) operate on the Caspian Sea, including: The ferries are mostly used for cargo; only the Baku–Aktau and Baku–Türkmenbaşy routes accept passengers. As an endorheic basin, the Caspian Sea basin has no natural connection with the ocean. Since the medieval period, traders reached