The Trigno River Mouth area, of great natural value, is a contact point between the river and coastal marine environments. The site, accessible from the Montenero Marina, is important for its abundant birdlife, some of which nest. Numerous educational and tourism activities are organized by organizations, associations, schools, businesses, and citizens.
The site encompasses the middle and lower reaches of the Trigno River, including the habitats of the riverbanks and valley slopes, and the Montenero Marina. The Trigno River has an almost torrential character; in fact, it appears as a torrent, characterized by a wide, pebbly riverbed with sparse riparian vegetation except in some stretches near the mouth, where riparian forests of willows and poplars are present. Also important is the presence of a priority habitat: sub-steppe paths of grasses and annual plants of the Thero-Brachypodietea genus.
The biotope's structure allows for the nesting of several charadriiform species, including the Little Ringed Plover and the Common Sandpiper, which are adapted to rapidly changing environments, such as riverbeds. Mediterranean scrub is absent, but pine forests have acquired high ecological and landscape value due to the presence, in the best-preserved areas, of an undergrowth of scrub species and thus a clear recovery of native vegetation.
The mouth area and the Montenero Marina fall within the boundaries of one of three Sites of Community Importance (SCIs) on the Molise coast. To preserve the landscape, flora, and fauna of this area, the European Life Maestrale Project has addressed the causes threatening the loss of habitats and species of Community interest in the Natura 2000 Network sites of the Molise coast. Actions are being undertaken to enhance and restore the natural heritage of these areas, as well as promoting best practices among coastal managers and users.