The Bouros-Kastri peninsula at the south-eastern tip of the Greek island of Euboia has previously been overlooked in the archaeological literature. This survey by the Southern Euboea Exploration Project, conducted under the aegis of the Canadian Institute in Greece, now provides a wealth of intriguing information about fluctuations in long-term use and habitation in this part of the Karystia. While the peninsula is agriculturally poor, its coast is blessed with several small coastal inlets and one important ancient port, Geraistos. These provide access to vital maritime routes and connect the peninsula to Athens and other Aegean ports. The survey revealed modest use of the peninsula during the Neolithic and Early Bronze Age; it was then virtually abandoned for the following two and a half millennia. Occupation resumed in the Late Archaic–Early Classical period, followed by near desertion in the 3rd century BC of all but some coastal sites, a resurgence of activity in the Late Roman period, and modest use in Byzantine and Ottoman times. The authors analyse the ways in which the peninsula's use was connected to that of the main urban centre at Karystos, and how the peninsula and the greater Karystia were integrated into the political, economic, and cultural spheres of Athens and the broader region.