The Orti-Bottagone marshes lie on the site of historic marsh areas of the lower Val di Cornia, themselves remnants of the ancient lake of Piombino, which disappeared from 1940 due to land reclamation. They are among the most important elements of a network of coastal wetlands along the Mediterranean flyway, due to their considerable size and position relative to other wetlands. The Site is composed of two contiguous but hydrobiologically different wetland areas: the brackish marsh of Orti, dominated by salicornia, and the freshwater marsh of Bottagone, characterized by reed beds, open water areas and flooded meadows. Despite being surrounded by industrial plants and divided by the busy road connecting Piombino to Follonica, the Site is an important biodiversity hotspot and habitat, especially for aquatic birds during their autumn and spring migrations and during nesting, moulting, and wintering periods. It serves as a stopover site for accidental species and hosts internationally endangered birds. The wetland also features an important population of greater flamingo (Phoenicopterus roseus). It is also a Special Area of Conservation under the European Union Habitats Directive, among other designations.