Montecristo, also Monte Cristo and formerly Oglasa, is an island in the Tyrrhenian Sea and part of the Tuscan Archipelago. Administratively it belongs to the municipality of Portoferraio in the province of Livorno, Italy. The island has an area of 10.39 km2 (4.01 sq mi), is approximately 4.1 km (2.5 mi) wide at its widest point, and is 3.4 km (2.1 mi) long; the coasts are steep, and extend for 16 km (9.9 mi). The island is a state nature reserve and forms part of the Tuscan Archipelago National Park.