The Samaria Gorge is the most visited tourist attraction in Chania, Crete and by far the most popular walk. More than a quarter million people walk through the gorge every year from May to October. In winter the gorge is closed to visitors due to danger posed by water and falling stones.
The Samaria gorge is the longest gorge one in Europe, 16 km. It is an area of stunning natural beauty. Rare flora and fauna have survived in this area and are protected. The mountains that have formed the gorge are wild, high and steep. One will pass through forests of ancient cypresses and pines and descend between vertical cliffs. The path starts from Xyloskalo (near Omalos) in the White Mountains at an altitude of 1230 meters and comes to an end at the village of Agia Roumeli at the Libyan sea. Walking through the gorge usually takes anything from 3 to 5 hours.
source: http://www.agiaroumeli.com