The WWF-Regional Nature Reserve Guardiaregia-Campochiaro is entirely located in the municipalities of Guardiaregia and Campochiaro in the province of Campobasso, Molise, on the side of the Matese. The protected area covers 3135 hectares of land, making it one of the larger areas in Italy between those managed by the WWF.
The reserve is characterized by the presence of three particular natural environments: the gorges of the River with the waterfall Quirino St. Nicholas, Mount Mutria and the karst area of the mountain Campochiaro. The Gorges of the River Quirino, located close to the town of Guardiaregia, form a narrow, deep incision between the town and the surrounding hills. Near Guardiaregia, the canyon of the Quirino Grand Valley receives the stream through the spectacular waterfall of St. Nicholas. The area of the mountain instead of Campochiaro has less tormented orography, has no high peaks, and culminates with Soglietta of fir trees, and has a constant tree cover spaced from the plateau area of Chianetta, Uma Valley, Pool Cul de Piana di Bove and Marianella. Finally, the spectacular phenomena of the underground caves of Pozzo della Neve that, for depth and breadth, are among the most impressive depths of Italy.