The Samaria Gorge hike is 15 kilometers, including 13 in the gorge itself and then 2 at the end to get to the town of Agia Roumeli. The hike begins near Omalos, with a series of downhill switchbacks, until you reach the dry riverbed, at which point much of the hiking is on stones of varying sizes. The full hike, with a lunch break (thank you to Hanim Lounge for the lunchbox!), took about six hours.
This is an easy day-long excursion from Chania. We caught the 7:45 am bus to Omalos (entrance to the gorge), hiked to Agia Roumeli, took the 5:15 boat to Chora Sfakion, and then rode the bus back to Chania, arriving around 8:30 pm. A long day, but a great and memorable day!