The Dead Sea (Salt Sea) is a lake located south of the Jordan River. It is called a sea because of its vast area and very high salinity. This is similar to the case where the Sea of Galilee was also called a sea.
In the photo above, the lower part is the Dead Sea. However, due to reduced water levels, the Dead Sea, which was originally one, has now split into two, upper and lower.
Meltwater from the perennial snows of Mount Hermon flows into the Sea of Galilee, then flows down the Jordan River and collects here in the Dead Sea.
The Dead Sea in the Bible
It appears to be near Siddim.
When the Israelites entered Canaan after the Exodus, God designated this place as the boundary of their territory.
Num 34:3Your southern boundary will start from the Salt Sea in the east and go along the edge of the Desert of Zin beside Edom.
Num 34:12The boundary will then go down the Jordan and end at the Salt Sea. This will be your land, with its boundaries on every side.