The Big River rises below Big Tree Hill within the Errinundra National Park, and flows generally westerly, joined by the Saint Patricks River, before reaching its confluence with the Brodribb River, in remote country southwest of the locality of Malinns in the Shire of East Gippsland. The river descends 101 metres (331 ft) over its 10-kilometre (6.2 mi) course.[2]