This is the boundary with Ukraine: mountains and the river Tisa.
This boundary is mainly Danube; and a in the South of Dobrogea a terrestrial border.
It is the Danube River.
The river Danube and the South Dobrogea.
The Potomac river
7
The western boundary of Romania is with Hungary.
The southern half of the eastern boundary of Alabama is the Chattahoochee River.
The Mediterranean Sea
The Atlantic Ocean forms the eastern boundary of the Southeast, while the Gulf of Mexico forms the southern boundary.
The 42nd parallel forms the southern boundary of Idaho. It marks the border between Idaho and Nevada as well as a portion of the border between Idaho and Oregon.
The northern boundary of Bulgaria that separates it from Romania is the Danube River. The Danube River is a very important river that flows through several countries before it reaches the Mediterranean Ocean.