Gulf of Agíou Orous, inlet of the Aegean Sea, northeastern Greece. It is the larger and deeper of two gulfs (the other being Ierisoú Gulf) that extend into the peninsula of the historical region in Greece known as Macedonia (Makedonía). The silted-up remains of a canal completed by Persian king Xerxes I in 480 bce link the two gulfs. The main community on the gulf is Ouranópolis, a stop for tourists exploring Mount Athos (Mount Ágio).