Aci Reale, a seaport town on the E. coast of Sicily, in the province of Catania, celebrated for its mineral waters; pop. in 1871, 35,787. It is situated on a hill of lava with a precipice over G50 feet high facing the sea, in the highly picturesque region between Mount Etna and Catania, 11m. N. N. E. of the latter, at the mouth of the small river Aci; is well built, principally of lava, and has many churches, convents, and towers. Great quantities of diaper are made. Near the town are the famous cave of Polyphemus and the grotto of Galatea.