A regional unit of Greek state that is located at the north of Macedonia, at the west of Epirus, at the east of Aegean Sea, Pagasetic and Thermaic Gulfs, at the south of Central Greece and the prefectures of Evrytania and Phthiotis.
Thessaly is a large valley surrounded by the mountains Olympus, Kamvounia (north), Othrys (south), Ossa and Pelion (east). Between Olympus and Kamvounia stands a gap that is a passage towards Macedonia. These mountain ranges were formed during the period that Thessaly used to be an internal sea (lake). The rivers and the torrents that were passing through, accumulated gradually gravels and sand that later would form Meteora rocks. Through the valley of Thessaly passes the river Pineios with its tributaries, as well as distinct torrents that spring from the mountains. Furthermore, a hill range divides the valley from the north to the south into the East (of Larissa) and the West Valley (of Trikala).
Its extent reaches the 13488 sq.km. and administratively is consisted of the following prefectures: Larissa, Trikala, Karditsa and Magnesia. To Thessaly appertain also north Sporades, except for Skyros.
The climate is continental, warm in summer and cold in winter, because of the mountains that surround the place which block the direct effect of the sea.