Formed by the confluence of the Bedford and Glen Erskine creeks, the Erskine Creek (officially designated a river[3]) rises below Mount Erskine, between Bullaburra and Wentworth Falls, and flows generally south, north-east, and east, before reaching its confluence with the Nepean River, near Mulgoa. The river descends 329 metres (1,079 ft) over its 21-kilometre (13 mi) course.[2]