Euboea is an island of Greece. It is also one of the 51 prefectures of Greece. Euboea is the second largest island of Greece. Its total area is 3,655 km2. It is to the east of Boeotia and Attica prefectures. The island is surrounded by the Aegean Sea. The capital of Euboea and the biggest city on the island is Chalkida.