1) International river of Europe 
The Veleka (Велека, Kocadere) is a river in the very southeast of Bulgaria (Burgas Province), as well as the very northeast of European Turkey. It is 147 km long, of which 123 km in Bulgaria and 25 km in Turkey, and takes it sources from a number of Karst springs in the Turkish part of the Strandzha (İstranca) mountain to flow into the Blac...