The extension of Orbetello's Lagoon is about 27 squared KM and it is 1 mt to 2 mt deep at list. It is separated from the sea by two sripes of land called tomboli and an artificial bridge connects Orbetello to Monte Argentario and splits the lagoon in two parts: The Est one and the west one.
Today the western part is protected by WWF but in the past the lagoon was considered the most important economic resourse of the town. Its waters rich of fish permitted to have seasons of fishing long and aboundant. Anguilla sfumata is a typical product of the town.

The lagoon is a humid area of international importance. Many species of birds (cavaliere d'italia, flamingos, ospreys, cormorants and gooses) nest or simply pass through it.

The WWF Oasis contains Patanella wood also, a green area having a very particular vegetation, mainly important for orchids.