Karystos in the context of Chalkis

The Triarchy of Negroponte was a crusader state established on the island of Euboea (Venetian: Negroponte) after the partition of the Byzantine Empire following the Fourth Crusade. Partitioned into three baronies (terzieri, "thirds") (Chalkis, Karystos and Oreos) run by a few interrelated Lombard families, the island soon fell under the influence of the Republic of Venice. From circa 1390, the island became a regular Venetian colony as the Realm of Negroponte (Venetian: Reame di Negroponte o Signoria di Negroponte).

Petalioi (Greek: Πεταλιοί) is an island complex in south-east of Euboea, in the homonymous gulf. It consists of 10 small islands and islets almost all uninhabited. The total area of the complex is 22.5 square kilometers. They belong to Karystos municipality, in Marmari municipal unit. The islands of the complex are: Megalonisos, Chersonisi, Avgo, Lamperousa, Louloudi, Makronisi, Pontikoniso, Praso, Tragos and Founti. The largest of them is Megalonisos. It has an area of 17 Km and is uninhabited. Most of them are privately owned and belong to Greek shipowners.

A tombolo is a sandy or shingle isthmus. It is a deposition landform by which an island becomes attached to the mainland by a narrow piece of land such as a spit or bar. Once attached, the island is then known as a tied island. The word tombolo is from the Italian tombolo, meaning 'pillow' or 'cushion', and sometimes translated incorrectly as ayre (an ayre is a shingle beach of any kind).

Several islands tied together by bars which rise above the water level are called a tombolo cluster. Two or more tombolos may form an enclosure (called a lagoon) that can eventually fill with sediment.

Carystus (/kəˈrɪstəs/; Greek: Κάρυστος, near modern Karystos) was a polis (city-state) on ancient Euboea. It was situated on the south coast of the island, at the foot of Mount Oche. It is mentioned by Homer in the Catalogue of Ships in the Iliad, as controlled by the Abantes. The name also appears in the Linear B tablets as "ka-ru-to" (identified as Carystus). Thucydides writes that the town was founded by Dryopes. According to the legend, its name was derived from Carystus, the son of Cheiron.