Berezan (Береза́нь; Ancient Greek: Borysthenes; former Pirezin) is an island in the Black Sea at the entrance of the Dnieper-Bug Estuary, Mykolaiv Raion, Mykolaiv Oblast, Ukraine. Located 8 kilometers from the city of Ochakiv and 4 kilometers from the resort village of Rybakivka. It is often being confused with the artificial island of Pervomaisky that is located within Dnieper-Bug Estuary. The Berezan island measures approximately 900 metres in length by 320 metres in width, the height of the northern part is 3-6 metres, the southern part is 21 metres. It is separated from the mainland (to which it may have been connected long ago) by about a mile and a half of shallow water. Berezan is an integral part of the historical and archaeological reserve of the National Academy of Sciences of Ukraine "Olvia". The island is uninhabited. In the summer, archaeological expeditions of the IA NASU and the State Hermitage Museum work here. The archaeological site is regularly destroyed as a result of unauthorized excavations. Berezan was home to one of the earliest Greek colonies (possibly known as Borysthenes, after the Greek name of the Dnieper) in the northern Black Sea region. The island was first settled in the mid-7th century B.C. and was largely abandoned by the end of the 5th century B.C., when Olbia became the dominant colony in the region. In the 5th century BC, Herodotus visited it to gather information about the northern course of the eponymous river. The colony thrived on wheat trade with the Scythian hinterland. In the Middle Ages, the island was of high military importance because it commanded the mouth of the Dnieper. During the period of Kievan Rus’ there was an important station on the trade route from the Varangians to the Greeks. It was there that Varangians first came into contact with the Greeks. The only Runic inscription in Southern Ukraine, the Berezan' Runestone, was found on the island in 1905, now on exhibit in the Odesa Historical Museum. The inscription seems to have been part of a gravestone over the grave of a Varangian merchant from Gotland.