Fira-Imerovigli-Oia
This is the classic hiking trail many people take every day. It will take you 3 hours to cover the 9 km distance from Fira to Oia. Altitude differences are not significant. The Caldera rim will keep you on the right track.
Follow the signs from Fira to the cable car. From there, continue uphill towards the Petros Nomikos Conference Centre. Within 20′, you will have reached Aghios Gerasimos, between Fira and Firostefani.
Follow the inland road, cross the picturesque Firostefani village and on your way to Imerovigli you will see the monastery of Aghios Nikolaos (St Nicholas), built in 1916.
After walking on the Caldera for about 10′, crossing Imerovigli, you will see the church of Aghios Georgios: it is worth making a stop here to admire the breathtaking view to the volcano.
Your next stop will be by the small church called Aghios Ioannis Katiforis, facing the rock of Skaros.
If you wish, go down the wide steps to walk the peninsula of Skaros where you will see few ruins of the medieval capital. From a path you can also reach the country church of Panagia Theoskepasti, west of Skaros. Return to Aghios Ioannis and follow the alley next to the church. You will pass by a line of newly built hotels and the first part of clear trail on the outskirts of Imerovigli will seem magical, awakening all your senses.
On the Caldera side, one of the shortcuts worth taking will lead you to Aghios Antonios (St Anthony), near the end of the lined-up hotels. After a 5-to 10-minute walk downhill, the stone-paved path will lead you to the sparkling white church. Return to the main road and go up to the right of Aghios Markos until you reach Prophet Elias above Imerovigli (a place easily accessible by car as well). The view is breathtaking, especially if you come at sunset.
For many people, the most beautiful part of the trail starts from Prophet Elias. There is a road sign showing the way to Oia, and you should go downhill until you reach the asphalt road on the crossroads to Pori beach. Follow the asphalt road for about 300 metres and you will see the trail starting again near the col.
From here on, take all your strength to climb the famous Mavro Vouno (Black Mountain), also well-known for its dazzling sunset. At the top, you will find the small church of Stavros (Cross): From here you can enjoy the wonderful view of Oia, and then start downhill towards Prophet Elias of Oia.
You will be there in 10′ and in another 5′ you will have reached the desalination plant. From there you can either follow the asphalt road to get to the village, or the small path.
Source: http://www.santorini.gr/