The landscape of Ukraine consists mostly of fertile plains (or steppes) and plateaus, crossed by rivers such as the Dnieper (), Seversky Donets, Dniester and the Southern Bug as they flow south into the Black Sea and the smaller Sea of Azov. To the southwest, the delta of the Danube forms the border with Romania. Ukraine's various regions have diverse geographic features ranging from the highlands to the lowlands. The country's only mountains are the Carpathian Mountains in the west, of which the highest is the Hora Hoverla at , and the Crimean Mountains on Crimea, in the extreme south along the coast. However Ukraine also has a number of highland regions such as the Volyn-Podillia Upland (in the west) and the Near-Dnipro Upland (on the right bank of Dnieper); to the east there are the south-western spurs of the Central Russian Upland over which runs the border with the Russian Federation. Near the Sea of Azov can be found the Donets Ridge and the Near Azov Upland. The snow melt from the mountains feeds the rivers, and natural changes in altitude form sudden drops in elevation and give rise to waterfalls.