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
United States of the Ionian Islands and Russia signed the Treaty of London, pledging the transfer of sovereignty to Greece upon ratification; this was meant to bolster the reign of the newly installed King George I of Greece. Thus, on 28 May, by proclamation of the Lord High Commissioner, the Ionian Islands were united with Greece. According to the second constitution of the republic (1803), Greek was the primary official language, in contrast to the situation in the Septinsular Republic. Italian was still in use, though, mainly for official purposes since the Venetian Republic. The only island in which Italian (Venetian) had a wider spread was