It extends for 118,144 hectares in the province of Foggia and includes the four Tremiti Islands (Marina Park Reserve) and Umbra Forest. Gargano terrotire is characterized by geological phenomenon of karstism, which over time generated over 4000 valleys (closed canals produced by the collapse of underground caves and the erosion of underwater waters), including Pozzatina valley, deep over 100 meters for a diameter of about 500, the largest in Europe. The few watercourses in Gargano are immersed in the lagoons of Lesina and Varano, two brackish water mirrors. In the territory of the Park there are 18 municipalities, interested in historical and natural trekking routes, many of which are also accessible to the disabled: "Gargano farms", "The hermits of silence", "Green gold of the Gargano", "Il Gargano dei Romani","Spring Routes","Saints and Orchids". This last route enhances Gargano as a hot spot of biodiversity for the presence of wild orchids, of which over 80 different species have been censored. To organize tourist attractions and scientific research, Park Authority has set up a number of equipped Visitor Centers and Trails.