Aetolia-Acarnania (Greek: Αιτωλοακαρνανία, Aitoloakarnanía) is one of the regional units of Greece. It is part of the geographic region of Central Greece and the administrative region of West Greece. A combination of the historical regions of Aetolia and Acarnania, it is the country's largest regional unit. Its capital is Missolonghi for historical reasons, with its biggest city and economic centre at Agrinio. The area is now connected with the Peloponnese peninsula via the Rio-Antirio Bridge. The surrounding regional units take in Arta in Epirus, a narrow length bordering Karditsa of Thessaly, Evrytania to the northeast, and Phocis to the east.
Mountains dominate the north, northeast, west and southeast, especially the Acarnanian Mountains. The longest and main river is the Acheloos, which ends as a delta in wetlands to the southwest on a rich fertile valley. The second longest is Evinos; others include the Ermitsa, the Inachos, and the Mornos (on the border with Phocis). The regional unit excludes the islands lying to its west, since they belong to the Kefalonia and Ithaca regional units. There is one reservoir and a lake in its central part. The many mountains of the area span the Panaitoliko toward the northeast and the Acarnanian Mountains, the Valtou and the Makrynoros mountains in the north, the Nafpaktia Mountains in the southeast, the Arakynthos and Kravara in the south.
Lakes include the Amvrakia, the Lysimachia, Ozeros, and Trichonida, and artificial lakes and reservoirs include Kastraki, Kremasta, the largest lake in Greece since its creation in 1970, and Stratos. Two lagoons are found in the southern part of the regional unit: the Messolongi and the Aitoliko.
The lowest altitude in Greece is found in west Aetolia-Acarnania at about -10 meters from the sea level.
Its climate tends toward hot summers and mild short winters in the low-lying areas, with cool winters dominating in the mountain areas. At the highest elevations, summers are cool, and snow and cold weather dominate the winter months in the Panaitoliko.
Main economic activities include agriculture – fisheries, tourism and other services (public and private sector). As in many other regions of Greece, production of wine and olive oil is significant. Dairy products are also important to the local economy as well as fish farming, unique to the area and a traditional source of income.