Lake Trichonida (Greek: Λίμνη Τριχωνίδα Limni Trichonida; Ancient Greek: Τριχωνίς Trichonis) is the largest natural lake in Greece.

It is situated in the eastern part of Aetolia-Acarnania, southeast of the city of Agrinio and northwest of Nafpaktos.

The Panaitoliko mountains are situated to the north and northeast of the lake.

The municipal units surrounding the lake are (from the east and clockwise) Thermo, Makryneia, Arakynthos, Thestieis, and Paravola.

Around the lake, there are beautiful forests with maples, pines, and other trees.