38.55°N 53°WThe Gulf of Euboea, Euboean Gulf, Euboic Sea or Euboic Gulf (Greek, Modern (1453-);: Ευβοϊκός Κόλπος|Evvoïkós Kólpos) is an arm of the Aegean Sea between the island of Euboea (northeast coastline) and the Greek mainland (southwest coastline). Trending diagonally northwest–southeast, the gulf is divided by the narrow Strait of Euripus, at the town of Chalcis. The North Euboean Gulf is about 50miles long and up to 15miles wide, and the South Euboean Gulf is about 30miles long, with a maximum width of 9miles.