Romania/Serbia: The Iron Gates

As the Danube winds its way from southern Germany to the Black Sea, it's rather inevitable that it would bump up against some mountains. Give a river a few million years, and it will wear a path to the sea. In this case, the resulting gorge in the Carpathian Mountains is called the Iron Gates, and it is a beautiful spot. 

Romania has its own Iron Gates National Park to protect its side of the river. It is the second-largest such park in the country, and protects birds, mammals and plants. Meanwhile, Derdap National Park is across the water in Serbia. 

Since the water isn't particular wide at this point in the river, it is deep instead. The countryside sure makes for a great place for a leisurely cruise. 

This will help you get the idea: