The lagoon of Messolonghi is the largest in Greece. It was created from deposits of loose materials of Acheloos river and the water is salty, which creates ideal conditions for salt marshes.
Inside the lagoon, there are 8 islands, many of which were used during the siege of Mesolongi and during the revolution of 1821. There are fish farms and the famous caviar production. The lagoon is protected from the Ramsar treaty and it is an environmental park.