Olza (river)
…Olza are: The river flows through the territory of Istebna in Poland, then crosses the Czech- Polish border and flows through territories of Bukovec, Písek, Jablunkov, Návsí, Hrádek, Bystřice, Vendryně, Třinec and Český Těšín. Here it begins to form the state border with Cieszyn, Pogwizdów and Kaczyce on…