The Dirillo, or Acate, is a 54-kilometre (34 mi) river in Sicily which springs from the Hyblaean Mountains and flows through the areas of Vizzini, Licodia Eubea, Mazzarrone, Chiaramonte Gulfi, Acate, Vittoria, Gela. It enters the Strait of Sicily south-east of the town of Gela. As the largest river in the area it is sometimes known as the Fiume Grande.The river was known in antiquity as the Achates. Theophrastus in his treatise On Stones (ca.