This is the most impressive gorge in central Crete, as regards both vegetation and geomorphology.

It cuts the imposing Psiloritis massif from north to south, linking the Forest of Rouvas to the valley of the River Koutsoulidis to the south, near Zaros, one of the loveliest large villages in Crete, known since antiquity for its springs.

At the northern entrance to the gorge stands the chapel of Agios Ioannis (St John), where the Forestry Service has constructed a picnic area. The gorge is four kilometres in length from the chapel of Agios Ioannis to the Monastery of Agios Nikolaos after which it is named, about one-and-a-half hours’ walk.

There is a path along most of the gorge, ending at the small Votomos Lake of Zaros to the south, one of the most important woodland recreation areas in central Crete. The gorge is one of the richest ecosystems in Greece and was even home to endemic Cretan wild goats until the turn of the 20th century.

Apart from its plant and animal life, however, the gorge also contains impressive geological features, in a rare landscape of imposing rock formations and beautiful ravines.

The ecological and geomorphological characteristics of the gorge, combined with its historical churches of Agios Nikolaos, Agios Minas and Agios Euthymios and the ruins of the Roman Aqueduct at the spot known as Sterna, which supplied ancient Gortyn with water, make it an important natural monument of Crete.