Montecristo, also known as Monte Cristo or formerly Oglasa, is an island located in the Tyrrhenian Sea. It is part of the Tuscan Archipelago and falls under the administrative jurisdiction of the municipality of Portoferraio in the province of Livorno, Italy.
The island covers an area of 10.39 km2 (4.01 sq mi) and measures approximately 4.1 km (2.5 mi) wide at its widest point and 3.4 km (2.1 mi) long. It is characterized by steep coasts that extend for a total of 16 km (9.9 mi). Montecristo serves as a state nature reserve and is a component of the Tuscan Archipelago National Park.