The Site is a large ecologically diverse wetland on the coast of northern Tuscany. It is a flat, mixed forest ecosystem, with soils formed by both sedimentation and erosion increased by wind and the hydrological interactions of the Arno and Serchio rivers and the sea. The Site includes the lower stretches of the two rivers, the wetlands of the old Arno delta, the lake of Massaciuccoli, and peatland floating on root mat islands. Wetlands of this size are extremely rare in coastal plains of the Mediterranean area. The Site hosts a great variability of communities and a wealth of species, including endemic subspecies such as Artemisia caerulescens cretacea, which is found only in central Italy, and Centaurea aplolepa subciliata, which is unique to the Tyrrhenian coast. The Site is an important migratory and wintering area for hundreds of bird species. It also contributes to carbon retention and is important for sediment retention, fresh water supply, and also recreation and nature-based tourism.