The Myrtoan (Mirtoan) Sea (Greek: Mυρτώο Πέλαγος, Myrtöo Pelagos) is a subdivision of the Mediterranean Sea that lies between the Cyclades and the Peloponnesos. It is described as the part of the Aegean Sea south of Euboea, Attica, and Argolis. [1] Some of the water mass of the Black Sea reaches the Myrtoan Sea, via transport through the Aegean Sea. (Saundry, Hogan & Baum.