The Myrtoan Sea (also Mirtoan Sea and Myrtoum Mare; Greek: Μυρτώο Πέλαγος, romanized: Mirtóo Pélagos Greek pronunciation: [mirˈto.o ˈpelaɣos]) is a subdivision of the Mediterranean Sea that lies between the Cyclades and Peloponnese.

It is described as the part of the Aegean Sea south of Euboea, Attica, and Argolis.

The Saronic Gulf, the gulf of Athens, lies between the Corinth Canal and the Myrtoan Sea.

It is said to have been named after the mythical hero Myrtilus, who was thrown into this sea by an enraged Pelops.

[2] The name has also been connected with that of the maiden Myrto.