Fonissa is a stream that forms a deep gorge from Vrysoules village to Loutro, in the municipality of Xylokatsro-Evrostini. In antiquity the stream was the natural borders of ancient Pellene, called Krios (ram). The name “fonissa” (female murderer) highlights how dangerous it is to be in its way when it is full of water. The only way to access the gorge is to follow the road from Kato Loutro village towards the monastery of Korfiotissa. Just before the monastery, turn left to the track descending to the stream. In every crossroad, turn in the direction of the antenna on the opposite hill. The track ends at the stream. Once at the dam, take the track that leads to Kato Loutro village.

It consists of a small yet impressive gorge that offers a trekking route of 10km. It is formed at the point where river that starts from Korfiotissa, is interrupted by a large limestone hill for 1.5 km before it reaches the Cornthian gulf. At some points it gets really narrow, acquiring the characteristics of a cave. It has an average width of 2-3 meters and has limestone hillsides.

Fonissa gorge was first made safe in 1984 by Spiros Apostolopoulos and Aris Theodoropoulos. Many other teams have continued the work ever since rendering the gorge safe and accessible. During the spring, water flows in the gorge, while the first narrow point is formed after the entrance. For almost one km (800m) the light gets scarce and the open points are few. The gorge offers 5 technical descendings, the biggest being 18m, and just before the exit the light appears again. Although equipment is required throughout the route, we can walk along it.

Fonissa offers 5 technical descendings, 250m difference in altitude, and 1.5km of length. A four member group requires three hours to cross it.