The island of Asinara, located at the north-western end of Sardinia, falls entirely within the territory of the Municipality of Porto Torres. It has an area of ​​approximately 51 square kilometers, a straight line length of over 17 km and over 100 km of coastline.

Due to its high historical and naturalistic importance, it became a National Park with Law no. 344 of 8 October 1997. The island was the site of a penal colony from 1885 and became a maximum security prison in the 1980s. The landscape is extremely diverse, with high cliffs on the west coast and large inlets and small beaches on the east coast.

The island of Asinara is also characterized by a scarce vegetation coat with a prevalent shrub maquis; only the area of ​​Elighe Mannu, where the only holm oak wood formation is located, has a small part covered by arboreal vegetation.

Various types of scrub are identified based on the prevailing species: mastic (Pistacia lentiscus), olive (Olea oleaster), euphorbia (Euphorbia dendroides), juniper (Juniperus phoenicea).
In the western coastal areas two bands of vegetation can be distinguished: one more exposed to the action of marine aerosol, is characterized by species such as Crithmum maritimum, Limonium acutifolium, Erodium corsicum, the other is characterized by the association with Centaurea horrida and Astragalus terracianoi.

On the island of Asinara there are various endemisms: there are about thirty species that represent 5% of the total flora, 3 are exclusive to Sardinia, 13 are common with Corsica, 14 are common with the other islands of the western Mediterranean. The exclusive ones are: Centaurea horrida, coastal endemism, species of ancient origin, protected by the Berne Convention, Limonium acutifolium present along the entire coast of the island, Limonium laetum, rare plant and in considerable decrease due to the type of habitat in which it lives (coastal ponds). Other particularly interesting endemisms are those that testify to the territorial continuity with the Sardinian-Corsican massif, some of which give a certain peculiarity to the flora of the island, such as: Astragalus terraccianoi, Erodium corsicum, Evax rotundata, Leucojum roseum, Nananthea perpusilla.

Today, over 80 species of terrestrial vertebrates belonging to the classes of Amphibians, Reptiles, Birds and Mammals are reported on the island and includes several rare and endangered species. Among the endemic species we can mention the luscengola, a curious scaled reptile, the Sardinian hare and the reddish crocidura, small rodents; among the Sardinian-Corsican species, the Sardinian barn owl, the wren, the flycatcher and the black bunting; the mouflon. Among the amphibians there are three species belonging to the order of the anurans: Raganella, Discoglosso, Emerald toad found near fountains and water reserves. Among the reptiles, 12 species have been reported, including the common tortoise, the Greek tortoise, the tiliguerta lizard, the snake and the snake snake.

Birds are among the best known animals on the island and have been studied for over 15 years, with colonial censuses and ringings to study the migratory flow. Since 1998 the Asinara has been included in the project called Small Islands coordinated by the National Institute for Wild Fauna, which has as its main purpose the study of the spring migration of trans-Saharan passerines. About 150 species were observed, of which 52 were found to nest. As many as 80 species are of European conservation interest: the lesser kestrel and the Corsican gull are of global interest. As many as 13 species are threatened, vulnerable or rare: (shearwater, queen's falcon, sandwich tern, sea jay, black redstart, black redstart, black redstart, greengrocer. 31 species have a purely European range: (osprey, kestrel, hawk, cuckoo, partridge sardinian, barn owl, owl). 38 species have a favorable conservation status: (shag, honey buzzard, robin, Sardinian magnanine, octopus). An introduced species, the magpie (Pica pica), brought by some inmates and bred as a companion animal.

As regards mammals, there are 11 species, equal to about 60% of the total Sardinian species: insectivores (hedgehog, mustiolo); a lagomorph (Sardinian hare); 5 rodents (oak mouse, wild mouse, rat black, brown rat, house mouse); ungulates (wild boar and mouflon). Donkeys deserve a special mention among the other species, including the Sardinian gray one and the characteristic white donkey of Asinara. The latter is famous for its small dimensions of about one meter in height for an adult specimen. Among the other species there are domestic ones, such as goats, with many individuals living in the wild throughout the island. There are also cattle, sheep, pigs and horses.

The marine environment constitutes an element of considerable scientific and naturalistic interest for Asinara. It is characterized by a high integrity and diversity of both plant and animal communities and by the excellent quality of its water.