The Machar Marshes are a large area of wetlands in the state of Upper Nile, South Sudan.
A 1950 study put the area of swamp at 6,500 km2.
[1] A 1980 study put the area of permanent swamp at 8,700 km2, 60% of which was grass and forest.
At times of high water they are also fed by spill from the Pibor River.
The marshes are drained by the Adar River, a tributary of the White Nile.