The Val di Cornia is the southernmost strip of the province of Livorno, located in the area between the Maremma Livornese and the Maremma Grossetana near the mouth of the river Cornia. The area is mainly hilly inland where it winds towards the south eastern slopes of the Colline Metallifere and the southern part of the province of Pisa. It is, however, flat along the coast except for the promontory of Piombino that separates the town from the Bay of Baratti.