The Dienvidsusēja (also known as Susēja or Suseja; Lithuanian: Susėja) is a river of Latvia and a right tributary of the river Mēmele. It flows for 114 kilometres. For 4.2 km, the river forms the border between Latvia and Lithuania. The river flows through Aknīste town, Nereta village and several smaller settlements.

• Zalvīte (36 km),
• Radžupe (21 km),
• Arālīte (21 km).

• List of rivers of Latvia