Samaria Gorge National Park, Crete

At 18km in length, the gorge (or farangi) is the largest in Europe.  Descending dramatically from the Omalos plateau, this natural wonder was formed by a river which flows between Mount Volakias to the west and the towering bulk of the Lefka Ori to the east which, over time, has sliced a steep, cavernous ravine between the two.