the Prut forms the border between Romania and Moldova.
The western border of Moldova is formed by the Prut river.
Nistru is the river on the east of Moldova, Prut separates Moldova from Romania, and the capital city is on the river Bic
Nistru (Dniester) and Prut.
The two countries sharing the Jordan river as a border are 1. Israel, west of the river and 2. Jordan, east of the river.
The border to the North, East and South is with Ukraine and is roughly 940 km long and follows, for part, the river Nistru (Dniester). The border to the West with Romania is roughyly 450 km long and follows the river Prut.
China.
The Danube River forms the border of some countries. They are Romania, Bulgaria, Hungary, Serbia, Slovakia, Austria and Germany.
The Black sea; the rivers Prut, Tisa and Danube.
The Mekong River forms a border between Thailand and Laos.
Mekong River
Well, Uruguay has the River Plate as its border with Argentina.
Rivers: Dunărea (Danube), Prut, TisaSea: Black Sea