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
Black Sea is a marginal sea and is the world's largest body of water with a meromictic basin. The deep waters do not mix with the upper layers of water that receive oxygen from the atmosphere. As a result, over 90% of the deeper Black Sea volume is anoxic water. The Black Sea's circulation patterns are primarily controlled by basin topography and fluvial inputs, which result in a strongly stratified vertical structure. Because of the extreme stratification, it is classified as a salt wedge estuary. The Black Sea only experiences water transfer with the Mediterranean Sea, so all inflow and outflow occurs