| Fonissa | |
| Subdivision Type1: | Country |
| Length Km: | 13.3 |
| Mouth Coordinates: | 38.101°N 22.5667°W |
The Fonissa (el|Φόνισσα) is a stream in western Corinthia, Peloponnese, Greece. It is 13.3km (08.3miles) long[1] and flows into the Gulf of Corinth. The source of the river is in the hills near the village Rethi. It flows a southeasterly direction through a narrow gorge, and empties into the Gulf of Corinth between the villages Kato Loutro and Kamari, 6 km northwest of Xylokastro.