Tisza

The Tisza is one of Central Europe's most important rivers, flowing through four countries: Serbia, Romania, Ukraine, and Hungary. Because it ran wholly within the Kingdom of Hungary, it was previously known as the Most Hungarian River. It is the second-longest river in Hungary.

The Tisza River flows from Rakhiv in Ukraine to the Danube in Serbia. Tisza Dam was erected in the 1970s to assist in flood control and water storage, but it has instead become one of Hungary's most famous tourist attractions. However, it was only recently that it was opened to international navigation following the country's accession to the European Union.

The Tisza River is also home to a diverse assortment of fauna, including 200 bird species. Pollution is the most serious threat to the Tisza River, where a series of pollution episodes caused by industrial spillage in Romania killed a large number of fish in the early 2000s.

Length: 600 miles (shared with Ukraine, Romania, Slovakia, and Serbia)