Lysimachia, Lisimachia, Lysimahia or Lisimahia is a lake located west of Agrinio
. The Acheloos river flows to the northwest with an artificial flow now to the east and an old natural flow near the lake. The area is 13.2 km², it is 17 km in length, its depth is around 9 m. East of the lake features another lake in the Great Aetolian Fields, the Trichonida which has an ecosystem. The lake offers a view of the city of Agrinio to the southeast.
The GR-5/E55 (Antirrio
- Agrinio - Ioannina) runs to the north and east, and the mountains covers the northern part, the mountains surround the lake and a valley is in the middle.
In the older times, the two lakes were one. The area was filled with many travelers between the 19th and the 20th centuries where the area around the lakes were filled with impenetrable forests. After the construction of the GR-5 (E55) which passes between the two lakes, canals and ditches were added. In Lysimachia has a stream known as Ermitsa (Ερμίτσα), the water from the lake empties into the Acheloos via the Dimikos (Δίμηκος) river. its nearest lake is Ozeros to the south.