The island has an area of 12 km2, is flat, with a maximum height of 16 metres (52 ft); it is green and marshy. Its waters are rich in fish, particularly some species of salmon, cod and crabs and it is part of the territory of the Kurils Nature Reserve.[1]
Polonsky Island is separated from Shikotan by the Spanberg Strait, to the southeast are the Oskolki islets. The island is separated from Zelyony Island, 11 kilometres (6.8 mi) southwest,[2] by the Polonskogo Strait.