Dvina Bay streams. There are many small islands in the Dvina Bay as well, the biggest being Mudyug Island. A national park, Onezhskoye Pomorye National Park, was open on the Onega Peninsula on 26 February 2013. The Dvina Bay is limited by the Onega Peninsula from the west. At the eastern side, the shore steeply rises to a plateau (White Sea - Kuloy Plateau) which drains east into the Soyana, a major tributary of the Kuloy. The Onega Bay shore is often referred to as "Letny Bereg" (Summer Coast), and the eastern shore of the bay is "Zimny Bereg" (Winter Coast). The
Onega River of the Onega is notable for the rapids, spread everywhere between Kargopol and Gorodok, and also located downstream from Porog (the name "Porog" means "a rapid"). The Onega basin area has an important historical and cultural significance. Kargopol is one of the oldest cities in Russian North (the traditional foundation date in the 12th century, first mentioned in the 14th century), and it still contains a big number of architectural and historical monuments. Oshevensk on the left bank of the Onega is the location of the former Alexandro-Oshevensky Monastery. Another historically important monastery in the Onega basin is the Kozheozersky