The island is located in the extreme south west of Sardinia and linked by a bridge and an artificial isthmus. Sant'antioco is the fourth largest island of the territory of the Italian Republic (108.9 km ²), immediately after the Elbe (Sant'Antioco has almost half the area of Elba), and prior to Pantelleria (km ² 83); in sixth place is the sister island of Sant'Antioco, the island of San Pietro. The island is largely of volcanic origin; It is now inactive for at least 15 ancient volcanism-20 million years. The island coast is mainly Rocky. In the West (offshore), the coast is characterized by vertical walls or very steep cliff, with spaced out caves and some creeks, with few but great beaches.