Adriatic Sea southeast, the Adriatic Sea connects to the Ionian Sea at the wide Strait of Otranto. The International Hydrographic Organization (IHO) defines the boundary between the Adriatic and the Ionian seas as a line running from the Butrinto River's mouth (latitude 39°44'N) in Albania to the Karagol Cape in Corfu, through this island to the Kephali Cape (these two capes are in latitude 39°45'N), and on to the Santa Maria di Leuca Cape (latitude 39°48'N). It extends from the northwest to the southeast and is wide. It covers and has a volume of . The Adriatic extends northwest from 40° to
Ionian Islands to the Ionian Islands Region except for Kythera, which belongs to the Attica Region. The seven islands are; from north to south: The six northern islands are off the west coast of Greece, in the Ionian Sea. The seventh island, Kythira, is off the southern tip of the Peloponnese, the southern part of the Greek mainland. Kythira is not part of the region of the Ionian Islands, as it is included in the region of Attica. In Ancient Greek the adjective "Ionios" () was used as an epithet for the sea between Epirus and Italy in which the Ionian Islands