That would be the Jordan River.
The two country is Israel and Jordan between the west bank.
Jordan
The West Bank borders Jordan, but not Syria.
It's on the west bank of the River Jordan. The country called Jordan is on the east bank.
Jericho.
The Dead Sea lies between Israel and The West Bank to the West, and Jordan to the East.
The Dead Sea lies between Israel and The West Bank to the West, and Jordan to the East.
The Dead Sea And the Jordan River
There are numerous cities in the West Bank, but none of them are exactly on the Jordan River. This is because the land is far too inclined to build any major cities. The closest major city to the river is Jericho. The most famous city in the West Bank is Jerusalem.
The Dead Sea between Israel, West Bank and Jordan.
The Jordan River. There is a small part of the Jordan River north of the West Bank that was part of the Israeli-Jordanian border. This has been greatly expanded since the Six-Day War of 1967, when Israel occupied the West Bank territory and acquired a much longer stretch of the Jordan River. Prior to that war the West Bank was part of Jordan & Jerusalem was a divided city. The Jordan River forms a large part of that international boundary (between Israel-West Bank and Jordan. South of the Dead Sea, the Israeli-Jordanian border follows the Wadi Arabah valley.
In the north, the border between Jordan and Israel or Jordan and the Israeli-Occupied West Bank is the Jordan River. However, the river ends at the Dead Sea. A far longer border in the desert between Jordan and Israel follows the Wadi Arabah from the Dead Sea to the Gulf of Aqabah.