According to the folk etymology, the name Ostrow Rzepowski (ostrow means islet) can be associated with legendary Rzepicha, the wife of Piast the Wheelwright, who was the father of the Piast dynasty (on the west shore of Lake Goplo, there is a village Rzepiszyn, named for Rzepicha).
Between the 8th and the 7th centuries BC, at the end of the Bronze Age, a settlement of the Lusatian culture existed on the islet. About the 7th century BC, it was converted into a fortified town surrounded by a wooden and earth embankment with a system of entanglements (stockades, breakwaters). Inside the town walls, a circular log road ran along the embankment, and terraced houses were in the yard. This town did not survive. It may have become depopulated because of some severe changes in the area’s climate and a considerable increase of the lake water level in the middle of the first millennium BC. It might also have happened because of Scythians invasion and numerous epidemics that ravaged the settlement.
Between the 14th and the 17th centuries, there was a cemetery on the islet.
After the irrigation of the upper Notec river between 1857 and 1859, the level of Goplo water rapidly decreased. It was then that Ostrow Rzepowski with the Castle Hill and the area outside town walls were connected (this led to the creation of the peninsula, which is popularly called Cypel by Kruszwica’s citizens), and the area of the former islet was converted into an orchard and a vegetable garden.
On the initiative of the Letnisko Society, established in 1922, a leisure complex was organized on the peninsula; it consisted of a bathing beach, baths, a restaurant and a band shell.
Lake Goplo
Goplo, a shallow postglacial flowing lake, situated in so called Goplo postglacial channel, is one of the well-known natural water bodies in Poland. It is the biggest lake of the Greater Poland-Kuyavian lake district and the 9th biggest lake in Poland. It is said that the water table at 77m.a.s.l. is 2,154.4ha in area; the islands are 25.5ha out of the area. The lake basin is 25km long and 200m up to 2000m wide. The average depth of the lake is 3.6m and the maximum depth is 16.6m. Goplo has a varied 87.5km long shoreline, which consists of numerous islets, bays and peninsulas.
In the past, the lake was much bigger in area, and its water table was called (according to the chronicle by Jan Dlugosz) Mare Polonorum, which means The Poles’ Sea.