Larissa: G. Length (Lon) 22o5'1 "/G. Width (Lat) 39o37'58"/Height 74m.
The city of Larissa is built on the two shores of Penios River at the centre of the eastern department of the Thessalian plain, which occupies almost the entire Prefecture of Larissa. The plain of Larissa is, with geological terms, very new. The basin was shaped at the Medium Pleistocene (210.000 - 45.000 years before our season), while the half of the plain took shape during the human presence in it, in the last 8.000 years.
North-easterly is extended Olympus mountain (2.918 m.), which is the tallest mountain of Greece and it is separated from the ravine of the torrent of Xirolakos or Ziliana in two big divisions, Upper Olympus, in the borders of Macedonia and Lower Olympus more southwards. Olympus with the mountain ranges of Titaros (1.839m.) and Kamvounia (1.615 m.) on the west, constitute the northern and north-western division of the Prefecture. South-easterly of Lower Olympus is raised Ossa or Kissavos mountain (1.978 m.). Is believed that it was linked with Olympus and then, because of geological changes, was created a crack between them. In this way was created the valley of Tempi. Southwards of the Prefecture and to north-western is raised a range of hills that includes the elevations of Halkodonio or Maurovouni (725 m.), Fillio (533 m.), Titanos (693 m.) and the mounts of Zarkos or Koutra (734 m.), leading in to the north to the ledge of Antihasia (1.416 m.). In the borders with the Prefecture of Fthiotida is raised the mount of Kasidiaris or Narthakion (1.011 m.).
Basic hydrographic element of the Prefecture of Larissa is Penios river, which enters in the plain of Larissa from the narrow pass Kalamaki and flows into Aegean Sea in the area of Tsagezi. Its main tributaries in the Prefecture are Titarisios and Enipeas.
In the Prefecture was existing also two important lakes, Karla and the Askiris or lake of Kallipefki. The first was shared in the Prefectures of Larissa and Magnesia, it had extent 180.000 acres and depth 4-6 m. Its vegetation was rich and it maintained appreciable fish and bird fauna. Was drained in 1962 aiming the fighting against epidemics, as the malaria, and the creation of cultivable extents, a fact that was fatal for the area and influenced drastically its climate. Thus, today is realized an effort for a partial reconstitution of the lake. The second was on 1.006 m. southwards of Kallipefki village, had extent 5.314 acres and its biggest depth was 12 m. The rich vegetation of canes and water-lilys that it had in its biggest part, was making difficult the fishery and consequently its economic exploitation. Because of this and the lack of cultivable extents, was decided its desiccation, which was completed in 1911. Today is discussed the reconstitution of this lake too. Thus in the region of Larissa does not exist a natural lake, only artificial tanks for the service of the irrigating needs of the Thessalian plain.
The eastern boundaries of the Prefecture of Larissa wets the Aegean Sea, creating a coastal area with about 60 km length. The beaches are characterized by big sandy extents and steep coasts in which are found small creeks and beaches with pebbles.