Diep River (Afrikaans Dieprivier), drains the area between the Kasteel Mountain (north of Malmesbury) and the northern slopes of the Durbanville Hills, in the Western Cape, a province of South Africa.

33°22′00″S 18°51′00″E / 33.3667°S 18.8500°E / -33.3667; 18.8500