This region is indented by the Toronaic Gulf and the Singitic Gulf, and one Corinthian colony in this region was hit by a tsunami while fighting the Persians and the site of a 430 Peloponnesian War battle. In addition to being the site of the cities of Acanthus and Potidaea, the three most prominent features of this region are the areas of Acte, Sithonia, and Pallene. Mt. Athos sits at the edge of one part of this region, and it was the site of an isthmus which was cut through by the Persian King Xerxes. For 15 points, 
This region is indented by the Toronaic Gulf and the Singitic Gulf, and one Corinthian colony in this region was hit by a tsunami while fighting the Persians and the site of a 430 Peloponnesian War battle. In addition to being the site of the cities of Acanthus and Potidaea, the three most prominent features of this region are the areas of Acte, Sithonia, and Pallene. Mt. Athos sits at the edge of one part of this region, and it was the site of an isthmus which was cut through by the Persian King Xerxes. For 15 points, identify this region of northern Greece known for its three finger-like peninsulas.
This region is indented by the Toronaic Gulf and the Singitic Gulf, and one Corinthian colony in this region was hit by a tsunami while fighting the Persians and the site of a 430 Peloponnesian War battle.
Chalcidice