The territory of Abruzzo is, roughly, the shape of a semicircle with a diameter of about 150 kilometres. The coastline, 129 kilometres long, stretches from the river Tronto to the Trigno and constitutes the eastern boundary of the region, while the North borders with Marche, the South with Molise and the West with Lazio. The land boundaries of the region are 467 kilometres long altogether.

The regional territory covers 10,794 square kilometres, the majority of which (65.1%, 7,027 square kilometres) is mountainous. 34.9% is constituted by hills. The statistics do not mention the plains. Near the coast, in fact, there are no plains, whereas inland there are a few, in the river's valley bottoms and also at high altitudes. The largest plain, the Piana del Fucino, can be considered "artificial" because it was the result of the drying up of the lake Fucino in the last century.

The territory of the four provinces of Abruzzo is divided in very different altimetric areas. The province of L'Aquila is totally characterized by mountains; in the Chieti area hills prevail, while in Pescara and Teramo the areas covered by mountains are more or less the same as those covered by hills.

The Appenine moutain range has a very varied aspect, and in Abruzzo is represented by numerous peaks, made all the more impressive since they can generally be viewed from low lying areas. There are numerous peaks in excess of 2,000m, the most important of which are Corne Grande 2,914m (Gran Sasso), Monte Armaro 2,795m, Corno Piccolo 2,655m, Monte Gorzano 2,458m, Monte Velino 2,487m, Monte Sirente 2,348m. The Abruzzo chain is characterised by a series of sub-chains interconnected by valleys and other erosion features.

Another type of feature is the high valley such as Majella, punctuated by glacial canyons of high naturalistic value. Some of the major features are l'Orfento, Santo Spirito, Selvaromana, Femmina Morta, and Taranta Peligna (all within Majella). Within other mountains can be found, Valley D'Angri, Voltigno valley, and the Chiarino Valley on Gran Sasso, Salinello gorge on mount Gemelli, Celano gorge on Sirente-Velino, and Fondillo valley in Abruzzo national park.

The mountains are generally wild and often inaccessible, rich in geologic and glacial features, with lower lying areas heavily forested where you can hear raging torrents and birdsong, or perhaps opening out onto green clearings where a pic-nic can be taken.

Other charactersitics of the Abruzzese Appenines are the presence of numerous green high plateaus, almost always used for grazing. The most important plateaus are Campo Imperatore, Rocche, and Cinquemiglia. Here the traditional agricultural activities have supplanted the original forests and therefore the countryside is essentially meadowland with spectacular spring flowers.

There are other plateaus with very diverse characters, here undulating and forested (mount Nuria, mountains Simbruini-Ernica), there flat and meadowed enriched by small mountain lakes.

The cliffs and peaks form a broad mosaic of varying alpine profile with a complex geography. For example Majella alone has approximately 60 peaks.

In the Gran Sasso group of peaks, at approximately 2,700m altitude  there still exists the only glacier of the entire appennine mountain chain, Calderone glacier, the most southerly in Europe and of enormous scientific value as an indicator in studies of climactic change.

In the western half of the region there is a series of mountainous chains (Laga, Gran Sasso, Velino, Sirente, Simbruini, Ernici, Majella and Monti Marsicani), with the highest peaks of the Apennine (Gran Sasso's Corno Grande, Majella's Monte Amaro, Monte Velino). Some of these chains are closer to the sea (Majella and east side of the Gran Sasso);with Monti Frentani, the closest to the Adriatic sea.

The Gran Sasso is made of a long ridge mainly orientated towards north-west and south-east, leaning southward from the Monte Siella to Forca di Penne. The majestic massif, indented and with very steep sides, grey and off-white in colour, rises from the karst plateau of Campo Imperatore (1600 mts high and 150 square kms wide) in  Dolomitic scenery, with pointed peaks, crests and vertical sides almost reaching up to 3000 metres. Among these is Corno Grande (2912 mts) where the only glacier of the Apennine survives : the Calderone, Corno Piccolo (2637 mts), Monte Brancastello (2560 mts), and Monte Aquila (2495 mts). The Gran Sasso joins north-west with the massif of the Monti della Laga, and the Vomano valley lies between them. The Laga mountains are covered in woods and their peaks reach almost 2500 metres, as in the case of the Gorzano (2458 mts),Pizzo di Sevo (2419 mts), or Monte di Mezzo and Monti della Laghetta (2369 mts), a real balcony over the Lake of Campotosto, the artificial basin at the service of the hydroelectrical plants of the Vomano valley and natural reserve, an oasis for many species of aquatic birds.

Hydrography

The Majella group is separated from the Gran Sasso by the Gole di Tremonti (or Gole di Popoli), carved by the Pescara river, and is situated close to the southern part of the coastline. The mountains of this group rise up directly from Chieti hills and from the valley of the Aventino river, the Pescara, of the Peligna plain (of Aterno-Pescara river) and of the maj or plateaus. They rise from the vast Peligna basin. Monte Amàro (2793 mts), the second highest peak of the Apennine after the Corno Grande, dominates the karst plateau of the Femmina Morta, about 4 kms long and, southward, an enormous dome of calcarean rock, marked by deep channels terminating in naked walls on the high eastern hills. Between the plain of the Fucino and the valley of L'Aquila stand aligned the chain of Sirente and the massif of Velino, one next to the other; north of these there is a series of main plateaus of the Apennine: Altopiano delle Rocche, Altopiano di Campo Felice, Prati del Sirente and Piani di Pezza. Similar formations exist south-west of the Majella, the so-called major plateaus, one of which is the Piano delle Cinquemiglia.

The plain of Fucino divides the chain of Velino-Sirente from a third one, which belongs only partially to Abruzzo, as it runs along the border of Lazio. It is formed by the extended group of Monti Simbruini and Ernici, a little over 2000 mts in height. Beyond the wide Valle Roveto, the chain reaches the south-western border of the region, joining the Mountains of the National Park of Abruzzo.