From a biological point of view, the Gargano promontory is actually an island, divided from the peninsula by the Tavoliere delle Puglie. It is rich in karst structures like caves and dolines. While in the past the promontory was entirely covered by forests, now they constitute only the 15 percent of its surface: the most important wood in the Park is the Foresta Umbra.

In the Park different kinds of habitat coexist: rocky coasts, great valleys rich in rare floral and faunal species, ancient beech woods, Mediterranean pine woods. Some of the trees growing in the Park are more than 500 years old. From a faunal point of view, the peculiarity of the Park is the presence of the roe deer and of several kinds of woodpeckers, among which the great -spotted woodpecker, the middle-spotted woodpecker, the lesser-spotted woodpecker, and the Lilford's woodpecker. The last two of them are very rare and, in Italy, they live only in protected areas, a fact which increases the naturalistic value of these forests.
Both the underwood and the prairies are rich in flowers: there are 56 orchid species, the highest number in Europe and in the Mediterranean basin. Moreover, in the past the promontory formed a connection with the Balkan flora and fauna, as it is evident from the presence of the so-called "trans-adriatic" species.