Lago di Sibolla is a small natural lake surrounded by a much larger marsh area and some meadows and woods. It is an integral part of a larger network of wetlands which also includes the Padule di Fucecchio and the Ex Lago e Padule di Bientina. The Site is important both for its plants, with relict species such as the water violet Hottonia palustris and habitats of conservation interest including forests of Italian oak Quercus pubescens, and for its animals, with notable species including the aquatic warbler (Acrocephalus paludicola). The nuclei of hygrophilous tree-shrub vegetation in the marsh area have been colonized by an increasing number of nesting species of herons and ibises, recently joined by the pygmy cormorant (Microcarbo pygmaeus). The lake now hosts the most important population of herons in peninsular Italy. The wetland is also important for wintering waterbirds, particularly the common teal (Anas crecca). It features a wealth of insect species and noteworthy reptiles such as the European pond terrapin (Emys orbicularis). Pollution and droughts, as well as weather extremes, are among the main threats. The Site is also a Special Area of Conservation under the European Union Habitats Directive, and a Regional Reserve.